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Competitive-Coding-2 Done #1152

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57 changes: 57 additions & 0 deletions Problem1.java
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Original file line number Diff line number Diff line change
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import java.util.Arrays;

// Bounded Knapsack
public class Problem1 {

public static void main() {
int target = 4;
int[] weights = {4, 5, 1};
int[] profits = {1, 2, 3};

int max = knapsackTabulation(target, weights, profits); //
System.out.println(max);

max = knapsackRecursive(target, weights, profits, 0); //
System.out.println(max);
}


public static int knapsackTabulation(int target, int[] weights, int[] profits) {
// Time Complexity : O(N^2)
// Space Complexity : O(N^2)
int rows = weights.length + 1;
int cols = target + 1;

int[][] table = new int[rows][cols];
for (int i = 1; i < rows; i++) {
int currentWeight = weights[i - 1];
for (int j = 1; j < cols; j++) {
if (currentWeight <= j) {
table[i][j] = profits[i - 1] + table[i - 1][j - currentWeight];
} else {
table[i][j] = table[i - 1][j];
}
}
}

return table[rows - 1][cols - 1];
}

static int knapsackRecursive(int target, int[] weights, int[] profits, int index) {
// Time Complexity : O(2^N), where N is the number of weights, at every recursion, we need to make choice whether to include weight or exclude weight
// Space Complexity : O(N)
if (index >= weights.length) return 0;
if (target <= 0) return 0;

int choose = 0;
if (weights[index] <= target) {
// choose the item only once and move the index to next item
choose = profits[index] + knapsackRecursive(target - weights[index], weights, profits, index + 1);
}

int notChoose = knapsackRecursive(target, weights, profits, index + 1);

return Math.max(choose, notChoose);
}

}
23 changes: 23 additions & 0 deletions Problem2.java
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import java.util.HashMap;
import java.util.Map;

public class Problem2{

public int[] twoSum(int[] nums, int target) {
// Time Complexity : O(N), N is number of elements in nums
// Space Complexity : O(N)
int [] result = new int[2];
Map<Integer, Integer> pairs = new HashMap<>();
for(int i = 0; i < nums.length; i++){
int complement = target - nums[i];
Integer index = pairs.getOrDefault(complement, null);
if( index == null){
pairs.put(nums[i], i);
}else {
result[0] = index;
result[1] = i;
}
}
return result;
}
}