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dzagalskiidzagalskii
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‎1.txt‎

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The current shape of the North American continent (the present-day territory of the United States of America and Canada) was formed 25,000 years ago. At that time the great northern icecap flowed over the North American continent. This ice flow determined the size and drainage of the Great Lakes. They changed the direction of the Missouri River and carved the channel of the Hudson River. They created the northern part of the Central Agricultural Basin, which is one of the richest farming areas in the world.
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On the Atlantic shore of the United States, much of the northern coast is rocky. But the middle and southern Atlantic coasts rise gently from the sea. The Appalachians, which run almost parallel to the east coast, are old mountains with many coal rich valleys between them To the west of the Appalachians, lie plateaus built up over the centuries from bits of stone that were washed down from the mountains and then cut into small hills by streams. Beyond is the great Central Lowland which resembles the plains of Eastern Europe.
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North of the Central Lowland, extending for almost 1,600 kilometers, are the five Great Lakes, which the United States shares with Canada. The lakes are considered to contain about half of the world�s fresh water. West of the Central Lowland are the Great Plains. They are stopped by the Rocky Mountains. The Rockies are young mountains. They are the same age as the Alps in Europe.

‎README.md‎

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Familiarization with the Hamming method of error-correcting coding, which allows to detect and automatically correct errors that occur during the transmission of information.

‎union_deheming.c‎

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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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int todec(int *byte);
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void invert(int *byte);
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void tobit(int x, int *byte);
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void kontrolbit(int *kod, int lengh);
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int main()
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{
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FILE *f = fopen("C:/laba/2.txt", "rb");
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FILE *t = fopen("C:/laba/3.txt", "w+b");
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int byte[8];
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printf("coded file: C:/laba/2.txt\n");
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printf("file: C:/laba/3.txt\n\n");
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printf("select decoding length 8/12/16/32/64: ");
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int c;
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scanf("%d", &c);
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if(c == 8)
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{
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int x, kod[12], g = 0;
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while(fgetc(f) != EOF)
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{
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fseek(f, -1, SEEK_CUR);
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x = fgetc(f);
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if((i != 0)&&(i != 1))
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kod[g++] = byte[i];
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}
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if(g == 12)
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{
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kontrolbit(kod, 12);
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g = 0;
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for(int i = 0; i < 12; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8))
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{
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byte[g++] = kod[i];
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}
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}
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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else if(c == 12)
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{
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int tmp[4], x, kod[17], g = 0, flag = 0, schet = 0;
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while(fgetc(f) != EOF)
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{
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fseek(f, -1, SEEK_CUR);
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x = fgetc(f);
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tobit(x, byte);
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kod[g] = byte[7];
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g++;
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if(g == 17)
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{
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g = 0;
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kontrolbit(kod, 17);
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g = 0;
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if(flag == 1) //костыль
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{
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for(int i = 0; i < 4; i++)
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{
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byte[g++] = tmp[i];
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}
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flag = 0;
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}
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for(int i = 0; i < 17; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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if((flag == 0)&&(schet%2 == 0)) //костыль 2
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{
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for(int i = 12; i < 17; i++)
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{
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if(i+1 != 16)
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{
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tmp[g++] = kod[i];
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}
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}
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flag = 1;
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}
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g = 0;
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}
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}
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g = 0;
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}
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schet++; //костыль 3
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}
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}
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else if(c == 16)
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{
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int x, kod[21], g = 0;
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while(fgetc(f) != EOF)
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{
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fseek(f, -1, SEEK_CUR);
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x = fgetc(f);
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if(i != 0)
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kod[g++] = byte[i];
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}
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if(g == 21)
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{
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kontrolbit(kod, 21);
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g = 0;
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for(int i = 0; i < 21; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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}
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}
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else if(c == 32)
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{
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int x, kod[38], g = 0;
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while(fgetc(f) != EOF)
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{
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fseek(f, -1, SEEK_CUR);
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x = fgetc(f);
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if((i == 6)||(i == 7))
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kod[g++] = byte[i];
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}
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if(g == 38)
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{
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kontrolbit(kod, 38);
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g = 0;
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for(int i = 0; i < 38; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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}
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}
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else if(c == 64)
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{
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int x, kod[71], g = 0;
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while(fgetc(f) != EOF)
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{
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fseek(f, -1, SEEK_CUR);
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x = fgetc(f);
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if(i == 7)
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kod[g++] = byte[i];
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}
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if(g == 71)
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{
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kontrolbit(kod, 71);
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g = 0;
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for(int i = 0; i < 71; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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}
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}
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fclose(f);
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fclose(t);
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printf("COMPLETE!");
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getchar(); getchar();
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return 0;
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}
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void kontrolbit(int *kod, int lengh)
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{
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int i = 0, summ = 0, errorpos = 0;
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while(i < lengh)
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{
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if((i+1 == 1)||(i+1 == 2)||(i+1 == 4)||(i+1 == 8)||(i+1 == 16)||(i+1 == 32)||(i+1 == 64))
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{
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int start = i;
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while(start < lengh)
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{
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for(int g = 0; g < i + 1; g++)
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{
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if((start+g != i)&&(start+g < lengh))
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summ = summ + kod[start+g];
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}
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start = start + i + i + 2;
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}
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if(kod[i] != summ%2)
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{
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errorpos = errorpos + i;
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}
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summ = 0;
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}
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i++;
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}
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if(errorpos != 0)
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{
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if(kod[errorpos] == 0)
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kod[errorpos] = 1;
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else
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kod[errorpos] = 0;
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}
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}
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void tobit(int x, int *byte)
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{
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for(int i = 0; i < 8; i++)
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{
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byte[i] = x%2;
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x = x/2;
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}
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invert(byte);
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}
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void invert(int *byte)
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{
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int tmp[8], g = 0;
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for(int i = 7; i > -1; i--)
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tmp[g++] = byte[i];
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for(int i = 0; i < 8; i++)
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byte[i] = tmp[i];
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}
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int todec(int *byte)
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{
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int x = 0, st = 7;
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for(int i = 0; i < 8; i++)
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{
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x = x + byte[i]*pow(2, st);
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st--;
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}
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return x;
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}

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