回溯法, 全排列生成问题, 枚举量不超过 n! 个.

#define S 4int n = S;int tot = 0;int C[S] = {
   0};void m_search(int cur) {    if ( cur == n ) {        tot += 1;        for ( int i = 0; i < n; i++ ) printf("%d ", C[i]); printf("\n");        return;    }    for ( int i = 0; i < n; i++ ) {        int ok = 1;        C[cur] = i;        for ( int j = 0; j < cur; j++ ) {            if (( C[cur] == C[j] ) ||               ( C[cur] == C[j] + (cur - j)) ||               ( C[cur] == C[j] - (cur - j))) {                    ok = 0;                break;            }        }        if ( ok ) m_search(cur+1);    }}int main() {    m_search(0);    printf("total: %d\n", tot);    return 0;}