Question

How to rearrange an array such that every second element becomes greater than its left and right element with C++

Answer 1

#include <iostream>

void swap(int arr[], int i, int j) {
    int temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}
 
void rearrangeArray(int arr[], int size) {
    for (int i = 1; i < size; i += 2) {
        // previous element is greater than current element
        if (arr[i - 1] > arr[i]) {
            swap(arr, i - 1, i);
        }
 
        // next element is greater than current element
        if (i + 1 < size && arr[i + 1] > arr[i]) {
            swap(arr, i + 1, i);
        }
    }
}
 
int main(void)
{
    int arr[] = { 1, 3, 6, 5, 4, 2, 9, 8, 7 };
    int size = sizeof(arr) / sizeof(arr[0]);
 
    rearrangeArray(arr, size);
 
    for (int i = 0; i < size; i++) {
        std::cout << arr[i] << " ";
    }
}


 
 
 
/*
run:
 
1 6 3 5 2 9 4 8 7 
 
*/

 

70+ SQL courses for beginners and professionals