nqueens tpa

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#define CHECK_ALLOC(p) if (p == NULL) {perror(""); exit(-1);}

bool isSafe(const int colPoses[], int row, int col) {
  for (int i = 0; i < row; i++) {
    if (col == colPoses[i] || abs(row - i) == abs(colPoses[i] - col)) {
      return false;
    }
  }
  return true;
}

void nqueens(int *colPoses, int row, int n, int *_cnt) {
  static int cnt = 0;
  if (!row) {
    colPoses = (int*)malloc(sizeof(int) * n);
    CHECK_ALLOC(colPoses);
  }
  if (row == n) {
    cnt++;
    return;
  }
  for (int col = 0; col < n; col++) {
    if (isSafe(colPoses, row, col)) {
      colPoses[row] = col;
      nqueens(colPoses, row + 1, n, _cnt);
      colPoses[row] = -1;
    }
  }
  if (!row) {
    free(colPoses);
    *_cnt = cnt;
    cnt = 0;
  }
}

int main(void) {
  int n, ans = 0;
  scanf("%d", &n);
  nqueens(NULL, 0, n, &ans);
  printf("%d\n", ans);
  return 0;
}