recusrion

RecursionDemos.java

@@ -0,0 +1,374 @@
+package june27;
+
+import java.util.ArrayList;
+
+public class RecursionDemos {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		// int[] one = {1, 1, 2, 2, 2, 3, 5};
+		// int[] two = {1, 1, 1, 2, 2, 4, 5};
+		// ArrayList<Integer> inter = getIntersection(one, two);
+		// System.out.println(inter);
+		// System.out.println(getSS("ab"));
+		// System.out.println(getPerm("abc"));
+		// System.out.println(getBoardPaths(0, 10));
+		// System.out.println(getMazePaths(0, 0, 2, 2));
+//		System.out.println(getMazePathsWD(0, 0, 2, 2));
+//		System.out.println(getMazePathsWDMultiSteps(0, 0, 2, 2));
+//		printSS("abc", "");
+//		printPerms("abc", "");
+
+//		printMP(0, 0, 2, 2, "");
+
+		ArrayList<String> list = getKPC("12");
+		for (String str : list)
+			System.out.println(str);
+
+		System.out.println(list.size());
+		System.out.println(getKpcCount("1312111113"));
+	}
+
+	public static int getKpcCount(String str) {
+		if (str.length() == 1) {
+			return getChoice(str.charAt(0)).length();
+		}
+
+		char ch = str.charAt(0);
+		String ros = str.substring(1);
+		int count = getKpcCount(ros);
+		return getChoice(ch).length() * count;
+	}
+
+	public static ArrayList<Integer> getIntersection(int[] one, int[] two) {
+		ArrayList<Integer> rv = new ArrayList<>();
+
+		return rv;
+	}
+
+	public static ArrayList<String> getSS(String s) {
+		if (s.length() == 0) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add(s);
+			return br;
+		}
+		char ch = s.charAt(0);
+		String ros = s.substring(1);
+
+		ArrayList<String> rr = getSS(ros);
+		ArrayList<String> mr = new ArrayList<>();
+		for (String rs : rr) {
+			mr.add(rs);
+			mr.add(ch + rs);
+			mr.add((int) ch + rs);
+		}
+
+		return mr;
+	}
+
+	public static ArrayList<String> getPerm(String s) {
+		if (s.length() == 0) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add(s);
+			return br;
+		}
+		char ch = s.charAt(0);
+		String ros = s.substring(1);
+
+		ArrayList<String> rr = getPerm(ros);
+		ArrayList<String> mr = new ArrayList<>();
+
+		for (String rs : rr) {
+			for (int i = 0; i <= rs.length(); i++) {
+				String ms = rs.substring(0, i) + ch + rs.substring(i);
+				mr.add(ms);
+			}
+		}
+
+		return mr;
+	}
+
+	public static ArrayList<String> getKPC(String s) {
+		if (s.length() == 0) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add(s);
+			return br;
+		}
+
+		char ch = s.charAt(0);
+		String ros = s.substring(1);
+
+		ArrayList<String> rr = getKPC(ros);
+		ArrayList<String> mr = new ArrayList<>();
+
+		String choices = getChoice(ch);
+		for (String rs : rr) {
+			for (int i = 0; i < choices.length(); i++) {
+				String ms = choices.charAt(i) + rs;
+				mr.add(ms);
+			}
+		}
+
+		return mr;
+	}
+
+	public static String getChoice(char key) {
+		if (key == '1') {
+			return "abc";
+		}
+		if (key == '2') {
+			return "def";
+		}
+		if (key == '3') {
+			return "ghi";
+		}
+		if (key == '4') {
+			return "jkl";
+		}
+		if (key == '5') {
+			return "mno";
+		}
+		if (key == '6') {
+			return "pqrs";
+		}
+		if (key == '7') {
+			return "tuv";
+		}
+		if (key == '8') {
+			return "wx";
+		}
+		if (key == '9') {
+			return "yz";
+		}
+		if (key == '0') {
+			return ".;";
+		}
+		return "";
+	}
+
+	public static ArrayList<String> getBoardPaths(int curr, int end) {
+		if (curr == end) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add("\n");
+			return br;
+		}
+
+		if (curr > end) {
+			ArrayList<String> br = new ArrayList<>();
+			return br;
+		}
+
+		ArrayList<String> mr = new ArrayList<>();
+
+		for (int dice = 1; dice <= 6; dice++) {
+			ArrayList<String> rrdice = getBoardPaths(curr + dice, end);
+			for (String rs : rrdice) {
+				mr.add(dice + rs);
+			}
+		}
+
+		return mr;
+	}
+
+	public static ArrayList<String> getMazePaths(int cr, int cc, int er, int ec) {
+		if (cr == er && cc == ec) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add("\n");
+			return br;
+		}
+
+		if (cr > er || cc > ec) {
+			ArrayList<String> br = new ArrayList<>();
+			return br;
+		}
+
+		ArrayList<String> mr = new ArrayList<>();
+
+		ArrayList<String> rrh = getMazePaths(cr, cc + 1, er, ec);
+		for (String rs : rrh) {
+			mr.add("H" + rs);
+		}
+
+		ArrayList<String> rrv = getMazePaths(cr + 1, cc, er, ec);
+		for (String rs : rrv) {
+			mr.add("V" + rs);
+		}
+
+		return mr;
+	}
+
+	public static ArrayList<String> getMazePathsWD(int cr, int cc, int er, int ec) {
+		if (cr == er && cc == ec) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add("\n");
+			return br;
+		}
+
+		if (cr > er || cc > ec) {
+			ArrayList<String> br = new ArrayList<>();
+			return br;
+		}
+
+		ArrayList<String> mr = new ArrayList<>();
+
+		ArrayList<String> rrh = getMazePathsWD(cr, cc + 1, er, ec);
+		for (String rs : rrh) {
+			mr.add("H" + rs);
+		}
+
+		ArrayList<String> rrv = getMazePathsWD(cr + 1, cc, er, ec);
+		for (String rs : rrv) {
+			mr.add("V" + rs);
+		}
+
+		if (cr == cc || cr + cc == ec) {
+			ArrayList<String> rrd = getMazePathsWD(cr + 1, cc + 1, er, ec);
+			for (String rs : rrd) {
+				mr.add("D" + rs);
+			}
+		}
+
+		return mr;
+	}
+
+	public static ArrayList<String> getMazePathsWDMultiSteps(int cr, int cc, int er, int ec) {
+		if (cr == er && cc == ec) {
+			ArrayList<String> br = new ArrayList<>();
+			br.add("\n");
+			return br;
+		}
+
+		if (cr > er || cc > ec) {
+			ArrayList<String> br = new ArrayList<>();
+			return br;
+		}
+
+		ArrayList<String> mr = new ArrayList<>();
+		int move = 1;
+
+		while (move <= ec) {
+			ArrayList<String> rrh = getMazePathsWDMultiSteps(cr, cc + move, er, ec);
+			for (String rs : rrh) {
+				mr.add("H" + move + rs);
+			}
+
+			move++;
+		}
+
+		move = 1;
+		while (move <= er) {
+			ArrayList<String> rrv = getMazePathsWDMultiSteps(cr + move, cc, er, ec);
+			for (String rs : rrv) {
+				mr.add("V" + move + rs);
+			}
+			move++;
+		}
+
+		move = 1;
+		while (move <= er && move <= ec) {
+			ArrayList<String> rrd = getMazePathsWDMultiSteps(cr + move, cc + move, er, ec);
+			for (String rs : rrd) {
+				mr.add("D" + move + rs);
+			}
+			move++;
+		}
+
+		return mr;
+	}
+
+	public static void printSS(String qst, String ans) {
+		if (qst.length() == 0) {
+			System.out.println(ans);
+			return;
+		}
+
+		char ch = qst.charAt(0);
+		String roq = qst.substring(1);
+
+//		System.out.println("Hello " + ch);
+
+		printSS(roq, ans + ""); // no
+
+//		System.out.println("From no to yes for: " + ch);
+
+		printSS(roq, ans + ch); // yes
+
+//		System.out.println("Bye " + ch);
+	}
+
+	public static void printSSWAscii(String qst, String ans) {
+		if (qst.length() == 0) {
+			System.out.println(ans);
+			return;
+		}
+
+		char ch = qst.charAt(0);
+		String roq = qst.substring(1);
+
+		printSSWAscii(roq, ans + ""); // no
+		printSSWAscii(roq, ans + ch); // yes
+		printSSWAscii(roq, ans + (int) ch); // ascii
+	}
+
+	public static void printPerms(String qst, String ans) {
+		if (qst.length() == 0) {
+			System.out.println(ans);
+			return;
+		}
+
+		for (int i = 0; i < qst.length(); i++) {
+			char ch = qst.charAt(i);
+			String roq = qst.substring(0, i) + qst.substring(i + 1);
+			printPerms(roq, ans + ch);
+		}
+	}
+
+	public static void printMP(int cr, int cc, int er, int ec, String ans) {
+		if (cr == er && cc == ec) {
+			System.out.println(ans);
+			return;
+		}
+
+		if (cr > er || cc > ec) {
+			return;
+		}
+
+		printMP(cr, cc + 1, er, ec, ans + "H");
+		printMP(cr + 1, cc, er, ec, ans + "V");
+		printMP(cr + 1, cc + 1, er, ec, ans + "D");
+	}
+
+	public void merge(int[] nums1, int m, int[] nums2, int n) {
+		int[] arr = new int[n + m];
+		int k = 0, i = 0, j = 0;
+
+		while (i < m && j < n && k < arr.length) {
+			if (nums1[i] < nums2[j]) {
+				arr[k] = nums1[i];
+				++k;
+				++i;
+			} else {
+				arr[k] = nums2[j];
+				++k;
+				++j;
+			}
+		}
+
+		while (i < m) {
+			arr[k] = nums1[i];
+			++i;
+			++k;
+		}
+
+		while (j < n) {
+			arr[k] = nums2[j];
+			++j;
+			++k;
+		}
+
+		for (int i1 = 0; i1 < arr.length; ++i1) {
+			nums1[i1] = arr[i1];
+		}
+	}
+
+}