Question

How to sort array into zig zag pattern (a < b > c < d > e < f > g) in C

Answer 1

#include <stdio.h>
#include <stdbool.h>

void swap(int* x, int* y) {
    int tmp = *x;
    *x = *y;
    *y = tmp;
}

void SortArrayIntoZigZagPattern(int arr[], int size) {
    bool small = true;

    for (int i = 0; i <= size - 2; i++) {
        if (small) {
            if (arr[i] > arr[i + 1])
                swap(&arr[i], &arr[i + 1]);
        }
        else {
            if (arr[i] < arr[i + 1])
                swap(&arr[i], &arr[i + 1]);
        }
        small = !small;
    }
}

int main()
{
    // a < b > c < d > e < f > g...
    // 3 < 5 > 1 < 9 > 6 < 7 > 2 < 4

    int arr[] = { 3, 5, 1, 7, 9, 6, 4, 2 };
    int size = sizeof(arr) / sizeof(arr[0]);

    SortArrayIntoZigZagPattern(arr, size);
    
    for (int i = 0; i < size; i++)
        printf("%2d", arr[i]);

    return 0;
}




/*
run:

 3 5 1 9 6 7 2 4

*/

 

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