Untitled

//12604 - N-Queens M-Rooks Problem   
#include <stdio.h>
#include <string.h>

int pos[10][2];//pos[位置的列數][是Queen還是Rook] = 位置的行數
int n, m;

int valid(int row, int level, int type){
    if(level - 1 < 0) return 1;
    for(int i = level-1; i >= 0; i--){
        for(int j = 1; j <= 2; j++){//1代表Queen 2代表Rook
            if(pos[i][j] != -1){//這一列的旗子是第j類
                if(j == 1 || (j == 2 && type == 1)){
                    if(pos[i][j] == row) return 0;
                    if(pos[i][j] - row == level - i) return 0;
                    if(row - pos[i][j] == level - i) return 0;
                }
                else if(j == 2){
                    if(pos[i][j] == row) return 0;
                }
            }
        }
    }
    return 1;
}

int solve(int q, int r, int level){

    int ans = 0;
    if(level == n+m) return 1;
    
    for(int i = 0; i < n+m; i++){
        if(valid(i, level, 1)){
            if(q-1 >= 0){
                pos[level][1] = i;
                ans += solve(q-1, r, level+1);
                pos[level][1] = -1;
            }
        }
        if(valid(i, level, 2)){
            
            if(r-1 >= 0){
                pos[level][2] = i;
                ans += solve(q, r-1, level+1);
                pos[level][2] = -1;
            }
        }
    }
    return ans;
}

int main(){

    while(scanf("%d%d", &n, &m) != EOF){

        memset(pos, -1, sizeof(pos));//上面沒有旗子時狀態為-1
        
        printf("%d\n", solve(n, m, 0));
    }
}