50127. Connect the Numbers

#include <stdio.h>
#include <stdlib.h>
#include "constructPointerArray.h"

typedef struct{
    int x;
    int y;
    int num;
} helper;

int cmp(const void* a, const void* b){
    helper* ha = (helper*)a;
    helper* hb = (helper*)b;
    return (ha->num) - (hb->num);
}

helper arr[1024 * 1024];

void constructPointerArray(const int a[1024][1024], const int *b[1024][1024], int n){
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            arr[i * n + j].x = i;
            arr[i * n + j].y = j;
            arr[i * n + j].num = a[i][j];
        }
    }
    qsort(arr, n * n, sizeof(helper), cmp);


    for(int i = 0; i < n * n - 1; i++){
        b[arr[i].x][arr[i].y] = &(a[arr[i + 1].x][arr[i + 1].y]);
    }
    b[arr[n * n - 1].x][arr[n * n - 1].y] = &(a[arr[0].x][arr[0].y]);
}