#Modification 90

amangit1314 · amangit1314 · commit 405cec7651b1 · 2021-10-03T15:55:56.000+05:30
diff --git a/README.md b/README.md
@@ -1,6 +1,6 @@
-# Java Placement Preparation DSA CRACKER SHEET 💻🦸‍♂️🐱‍👤[179/450]
+# Java Placement Preparation DSA CRACKER SHEET 💻🦸‍♂️🐱‍👤[181/450]
 
-🐼 This is a full fled-ged repository for learning Java Language & DSA for Placement Preparation.
+☄ This is a full fled-ged repository for learning Java Language & DSA for Placement Preparation.
 
 💪 Here you can find the solution's of **_450 Questions of (Data Structure & Algorithms Cracker Sheet)_** By **LOVE BABBAR** Bhaiya.
 
diff --git a/backtracking/Print_All_Permutations.java b/backtracking/Print_All_Permutations.java
@@ -0,0 +1,53 @@
+package backtracking;
+import java.util.*;
+
+// Problem Title => Print all permutations of string
+public class Print_All_Permutations{
+
+    // Swap characters at position
+    // @param a string value
+    // @param i position 1
+    // @param j position 2
+    // @return swapped string
+    public String swap(String a, int i, int j){
+        char temp;
+        char[] charArray = a.toCharArray();
+        temp = charArray[i];
+        charArray[i] = charArray[j];
+        charArray[j] = temp;
+        return  String.valueOf(charArray);
+    }
+
+    // permutation function
+    // @param str string to calculate permutation for
+    // @param 1 starting index
+    // @param r and index
+    private void permute(String str, int l, int r){
+        if(l == r)
+            System.out.println(str);
+
+        else{
+            for(int i = 1; i <= r; i++){
+                str = swap(str, l, i);
+                permute(str, l+1, r);
+                str = swap(str, l, i);
+            }
+        }
+    }
+
+    // Driver Function
+    public static void main(String[] args) {
+        // scanner object for talking inputs
+        Scanner sc = new Scanner(System.in);
+
+        // Asking user for String str as input
+        String str = sc.nextLine();
+        int n = str.length();
+
+        // Making an object of Print_All_Permutations class
+        Print_All_Permutations permutation = new Print_All_Permutations();
+
+        // Permute the array or printing the permutation's
+        permutation.permute(str, 0, n-1);
+    }
+}
diff --git a/stack_and_queue/P38.java b/stack_and_queue/P38.java
@@ -0,0 +1,62 @@
+package stack_and_queue;
+import java.util.*;
+import java.util.Stack;
+import java.lang.*;
+
+// Problem Title => Next Smaller Element
+public class P38 {
+    
+    // prints element and NSE pair for all elements of arr[] of size n
+    public static void printNSE(int[] arr, int n){
+        Stack<Integer> s = new Stack<>();
+
+        // push the first element to stack
+        s.push(arr[0]);
+
+        // iterate for rest of the elements
+        for(int i = 1; i < n; i++){
+            if(s.empty()){
+                s.push(arr[i]);
+                continue;
+            }
+
+            // if stack is not empty,
+            // then pop an element from stack.
+            // If the popped element is greater than next, then
+            // (a) print the pair,
+            // (b) keep popping while elements are greater and stack is not empty.
+            while(!s.empty() && s.peek() > arr[i]){
+                System.out.println(s.peek() + " --> " + arr[i]);
+                s.pop();
+            }
+
+            // push next to stack so that we can find next smaller for it
+            s.push(arr[i]);
+        }
+
+        // After iterating over the loop,
+        // the remaining elements in stack do not have the next smaller element,
+        // so print -1 for them
+        while(!s.empty()){
+            System.out.println(s.peek() + " --> " +  "-1");
+            s.pop();
+        }
+    }
+
+    // Driver function
+    public static void main(String[] args) {
+        // Scanner object for input
+        Scanner sc = new Scanner(System.in);
+
+        // Taking Size of the array as input from user
+        int n = sc.nextInt();
+
+        // Taking the elements of array as input from user
+        int[] arr = new int[n];
+        for(int i = 0; i < n; i++)
+            arr[i] = sc.nextInt();
+
+        // Printing the Next Smaller Element by calling printNSE method
+        printNSE(arr, n);
+    }
+}
