Create Stack using Two Queue

Peak_Element_CPP

@@ -0,0 +1,33 @@
+// A C++ program to find a peak element
+#include <bits/stdc++.h>
+using namespace std;
+
+// Find the peak element in the array
+int findPeak(int arr[], int n)
+{
+    // first or last element is peak element
+    if (n == 1) 
+      return arr[0];
+    if (arr[0] >= arr[1])
+        return 0;
+    if (arr[n - 1] >= arr[n - 2])
+        return n - 1;
+
+    // check for every other element
+    for (int i = 1; i < n - 1; i++) {
+
+        // check if the neighbors are smaller
+        if (arr[i] >= arr[i - 1] && arr[i] >= arr[i + 1])
+            return i;
+    }
+}
+
+// Driver Code
+int main()
+{
+    int arr[] = { 1, 3, 20, 4, 1, 0 };
+    int n = sizeof(arr) / sizeof(arr[0]);
+    cout << "Index of a peak point is "
+         << findPeak(arr, n);
+    return 0;
+}

Stack using Two Queue

@@ -0,0 +1,94 @@
+#include<iostream>
+using namespace std;
+
+struct qu1// queue1 declaration {
+   qu1 *n1;
+   int d1;
+}*f1 = NULL, *r1 = NULL, *q1 = NULL, *p1 = NULL, *np1 = NULL;
+
+struct qu2// queue2 declaration {
+   qu2 *n2;
+   int d2;
+}*f2 = NULL, *r2 = NULL, *q2 = NULL, *p2 = NULL, *np2 = NULL;
+
+void enqueue1(int a) {
+   np1 = new qu1;
+   np1->d1 = a;
+   np1->n1 = NULL;
+   if (f1 == NULL) {
+      r1 = np1;
+      r1->n1 = NULL;
+      f1 = r1;
+   } else {
+      r1->n1 = np1;
+      r1 = np1;
+      r1->n1 = NULL;
+   }
+}
+
+int dequeue1() {
+   int a;
+   if (f1 == NULL) {
+      cout<<"no elements present in queue\n";
+   } else {
+      q1 = f1;
+      f1 = f1->n1;
+      a = q1->d1;
+      delete(q1);
+      return a;
+   }
+}
+
+void enqueue2(int a) {
+   np2 = new qu2;
+   np2->d2 = a;
+   np2->n2 = NULL;
+   if (f2 == NULL) {
+      r2 = np2;
+      r2->n2 = NULL;
+      f2 = r2;
+   } else {
+      r2->n2 = np2;
+      r2 = np2;
+      r2->n2 = NULL;
+   }
+}
+
+int dequeue2() {
+   int a;
+   if (f2 == NULL) {
+      cout<<"no elements present in queue\n";
+   } else {
+      q2 = f2;
+      f2 = f2->n2;
+      a = q2->d2;
+      delete(q2);
+      return a;
+   }
+}
+
+int main() {
+   int n, a, i = 0;
+   cout<<"Enter the number of elements to be entered into stack\n";
+   cin>>n;
+   while (i < n) {
+      cout<<"enter the element to be entered\n";
+      cin>>a;
+      enqueue1(a);
+      i++;
+   }
+   cout<<"\n\nElements popped\n\n";
+   while (f1 != NULL || f2 != NULL)// if both queues are not null {
+      if (f2 == NULL)// if queue 2 is null {
+         while (f1->n1 != NULL) {
+            enqueue2(dequeue1());
+         }
+         cout<<dequeue1()<<endl;
+      } else if (f1 == NULL)//if queue 1 is null {
+         while (f2->n2 != NULL) {
+            enqueue1(dequeue2());
+         }
+         cout<<dequeue2()<<endl;
+      }
+   }
+}

Toogle_bits_given_range.cpp

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+// C++ implementation to toggle bits in
+// the given range
+#include <bits/stdc++.h>
+using namespace std;
+
+// function to toggle bits in the given range
+unsigned int toggleBitsFromLToR(unsigned int n,
+                                unsigned int l, unsigned int r)
+{
+    // calculating a number 'num' having 'r'
+    // number of bits and bits in the range l
+    // to r are the only set bits
+    int num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1);
+
+    // toggle bits in the range l to r in 'n'
+    // and return the number
+//Besides this, we can calculate num as: num=(1<<r)-l .
+    return (n ^ num);
+}
+
+// Driver program to test above
+int main()
+{
+    unsigned int n = 50;
+    unsigned int l = 2, r = 5;
+    cout << toggleBitsFromLToR(n, l, r);
+    return 0;
+}