Merge pull request #2 from prashant3360/prashant3360-patch-2

Added PermutationOfString code file

Author: prashant3360

Practice Problems/Backtracking/PermutationsOfString/PermutationsOfString.java

@@ -0,0 +1,48 @@
+import java.util.HashSet;
+
+public class PermutationsOfString {
+
+	public static void main(String args[]) {
+
+		String input = "ABC";
+		HashSet<String> resultSet = new HashSet<String>();
+
+		permutation(input, 0, resultSet);
+
+		for (String str : resultSet) {
+			System.out.println(str);
+		}
+
+	}
+
+	public static void permutation(String input, int fixedIndex, HashSet<String> resultSet) {
+
+
+		if (fixedIndex == input.length()-1) {
+			resultSet.add(input);
+			return;
+		}
+
+		for (int i = fixedIndex; i < input.length(); i++) {
+
+			input = swap(input, fixedIndex, i);
+			resultSet.add(input);
+			permutation(input, fixedIndex+1, resultSet);
+			input = swap(input, fixedIndex, i);
+
+		}
+
+	}
+
+	public static String swap(String s, int i, int j) {
+
+		char[] input = s.toCharArray();
+
+		char temp = input[i];
+		input[i] = input[j];
+		input[j] = temp;
+
+		return String.valueOf(input);
+	}
+
+}