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Find majority element in an array (Boyer–Moore majority vote algorithm).cpp

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+#include <iostream>
+#include <vector>
+#include <unordered_map>
+using namespace std;
+
+template<size_t  n>
+int majorityElement(int (&A)[n])
+{
+    unordered_map<int, int> map;
+    int max = 0;
+    int element ;
+    for (int i = 0; i < n; i++) {
+        map[A[i]]++;
+        if (max < map[A[i]]){max = map[A[i]];element = A[i];}
+    }
+    if(max > n / 2)     cout << "Majority is present and its held by : " << element;
+    else cout <<" No majority";
+
+}
+
+// main function
+int main()
+{
+    int A[] = { 2, 8, 7, 2, 2, 5, 2, 3, 1, 2, 2 };
+
+    majorityElement(A);
+
+    return 0;
+}

Find pair with given sum in an array.cpp

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+#include <iostream>
+#include <unordered_map>
+using namespace std;
+template <size_t  n>
+void  findPair(int (&arr)[n], int sum){
+    unordered_map <int,int> map;
+    for (int i = 0; i < n; ++i) {
+        if(map.find(sum - arr[i]) != map.end()){ cout << "Pairs Found They are at index: " << map[sum-arr[i]]  <<" and " << i <<" ( " << arr[map[sum-arr[i]]] <<" , " << arr[i] <<" )" <<"\n"; return;}
+
+        map[arr[i]] = i;
+    }
+    cout << "Not found";
+}
+int main(){
+    int arr[] = { 8, 7, 2, 5, 3, 1};
+    int sum = 10;
+    findPair(arr, sum);
+    return 0;
+}

Shuffle a given array of elements (Fisher–Yates shuffle).cpp

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+#include <stdio.h>
+#include <time.h>
+#include <random>
+void swap(int A[], int i, int j) {
+    int temp = A[i];
+    A[i] = A[j];
+    A[j] = temp;
+}
+
+template  <size_t n>
+void shuffle(int (&A)[n])
+{
+    for (int i = n-1; i >= 1; i--) {
+        int j = rand() % i+1;
+        printf("%d ",j);
+        swap(A,i,j);
+    }
+}
+
+// main function
+int main(void)
+{
+    int A[] = { 1, 2, 3, 4, 5, 6 };
+    srand(time(NULL));
+    shuffle(A);
+    printf("\n");
+    for (int i = 0; i < (*(&A+1) - A); i++)     printf("%d ", A[i]);
+    return 0;
+}

determine any sub array with sum 0.cpp

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+#include <iostream>
+#include <unordered_set>
+using namespace std;
+
+template<size_t  n>
+int findAnySubArrayWithSum0(int (&arr)[n])
+{
+    unordered_set<int> sumSet;
+    int sum = 0;
+    for (int i = 0 ; i < n ; i++)
+    {
+        sum += arr[i];
+        if (sum == 0 || sumSet.find(sum) != sumSet.end())   return 1;
+        sumSet.insert(sum);
+    }
+    return 0;
+}
+
+// main function
+int main()
+{
+    int arr[] = { 3, 4, -7, 3, 1, 3, 1, -4, -2, -2 };
+    if(findAnySubArrayWithSum0(arr)) cout << "Yes";
+    else cout << "No";
+    return 0;
+}