C语言-N皇后问题

#include 
#include 
#include 

#define N 8

int solveNQueens(int n);
void printSolution(int* queens, int n);
void backtrack(int* queens, int n, int row, int* columns, int* diagonals1, int* diagonals2, int* solutionNum);

int main() {
    clock_t start = clock();
    printf("The are %d solutions to the %d Queens Problem.n", solveNQueens(N), N);
    clock_t stop = clock();
    printf("The running time is %.3fs", (double)(stop - start) / CLOCKS_PER_SEC);
    return 0;
}

void printSolution(int* queens, int n) {
    printf("(");
    for (int i = 0; i < n - 1; i++) {
        printf("%d, ", queens[i]);
    }
    printf("%d)n", queens[n - 1]);

    return;
}

void backtrack(int* queens, int n, int row, int* columns, int* diagonals1, int* diagonals2, int* solutionNum) {
    if (row == n) {
        (*solutionNum)++;
       printSolution(queens, n);
    } else {
        for (int i = 0; i < n; i++) {
            int diagonal1 = row - i + n - 1;
            int diagonal2 = row + i;
            if (columns[i] || diagonals1[diagonal1] || diagonals2[diagonal2]) {
                continue;
            }

            queens[row] = i;
            columns[i] = 1;
            diagonals1[diagonal1] = 1;
            diagonals2[diagonal2] = 1;

            backtrack(queens, n, row + 1, columns, diagonals1, diagonals2, solutionNum);

            queens[row] = -1;
            columns[i] = 0;
            diagonals1[diagonal1] = 0;
            diagonals2[diagonal2] = 0;
        }
    }
}

int solveNQueens(int n) {
    int solutionNum = 0;
    int queens[n];
    int columns[n];
    int diagonals1[n + n];
    int diagonals2[n + n];
    memset(queens, -1, sizeof(queens));
    memset(columns, 0, sizeof(columns));
    memset(diagonals1, 0, sizeof(diagonals1));
    memset(diagonals2, 0, sizeof(diagonals2));

    backtrack(queens, n, 0, columns, diagonals1, diagonals2, &solutionNum);

    return solutionNum;
}