Add backtracking solution

Author: MadhavBahl

day10/JavaScript/sol.js

@@ -24,4 +24,4 @@ function permut(string) {
     return permutations;
 }
 
-permut('123');
+console.log(permut('1234'));

day10/JavaScript/stringPermute.js

@@ -0,0 +1,22 @@
+function stringPermutations (str) {
+    let permutations = [];
+
+    if (str.length <= 1) {
+        permutations.push (str);
+        return permutations;
+    } else {
+        for (let i=0; i<str.length; i++) {
+            let start = str[i],
+                remainingString= str.slice(0, i) + str.slice(i+1),
+                permutationsforRemainingString = stringPermutations(remainingString);
+            
+            for (let j=0; j<permutationsforRemainingString.length; j++) {
+                permutations.push (start + permutationsforRemainingString[j]);
+            }
+        }
+    }
+
+    return permutations;
+}
+
+console.log (stringPermutations('123'));

day10/JavaScript/stringPermute2.js

@@ -0,0 +1,32 @@
+/**
+ * METHOD -- Backtracking
+ * Algorithm taken from GeeksForGeeks (https://www.geeksforgeeks.org/write-a-c-program-to-print-all-permutations-of-a-given-string/)
+ * Implemented in JS by @MadhavBahlMD
+ * @date 02/01/2019
+ */
+
+function swap (str, pos1, pos2) {
+    // console.log (`pos1 = ${pos1}, pos2 = ${pos2} old`, str);
+    str = str.split('');
+    let temp = str[pos1];
+    str[pos1] = str[pos2];
+    str[pos2] = temp;
+    str = str.join('');
+    // console.log ('new str', str);
+    return str;
+}
+
+function stringPermutations (str, start, end) {
+    if (start === end) {
+        console.log (str);
+    } else {
+        for (let i=start; i<end; i++) {
+            str = swap (str, start, i);
+            stringPermutations (str, start+1, end);
+            str = swap (str, i, start);
+        }
+    }
+}
+
+let inputStr = '123';
+stringPermutations (inputStr, 0, inputStr.length);