递归_百炼 1321 棋盘问题

Posted 2020-10-22 mapreduce

 1 #define _CRT_SECURE_NO_WARNINGS  
 2 #include <stdio.h>
 3 #include <math.h>
 4 #include <algorithm>
 5 #include <stdlib.h>
 6 #include <vector>
 7 #include <map>
 8 #include <queue>
 9 #include <string>
10 #include <iostream>
11 #include <ctype.h>
12 #include <string.h>
13 #include <set>
14 #include <stack>
15 #include<functional>
16 using namespace std;
17 #define Size 10
18 #define maxn  1<<30
19 #define minn  1e-6
20 char a[Size][Size];
21 int dis[Size];//标记第i列放没放元素
22 int len;
23 int ans = 0;
24 void solve(int row, int k){
25     if (k == 0) {
26         ans++;
27         return;  //达到结束条件时候一定要return,不要再往下执行了
28     }
29     if (row > len) return;
30     solve(row + 1, k);//有可能这一行不放棋子也能满足要求
31     for (int i = 1; i <= len; i++){//列
32         if (a[row][i] == ‘#‘&&dis[i] == 0){
33             dis[i] = 1;
34             solve(row+1, k - 1);
35             dis[i] = 0;
36         }
37     }
38 }
39 int main(){
40     int k;
41     while (cin >> len >> k){
42         ans = 0;
43         for (int i = 1; i <= len; i++)
44             dis[i] = 0;
45         if (len == -1 || k == -1) break;
46         for (int i = 1; i <= len; i++)
47             for (int j = 1; j <= len; j++)
48                 cin >> a[i][j];
49         solve(1, k);
50         cout << ans << endl;
51     }
52 }