Educational Codeforces Round 1(D. Igor In the Museum) (BFS+离线访问)

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm>
 5 #include <queue>
 6 
 7 using namespace std;
 8 char map[MAXN][MAXN];
 9 bool ok[MAXN][MAXN];
10 int ans[MAXN][MAXN];
11 int n , m , res , tx[] = {-1 , 0 , 1 , 0} , ty[] = {0 , 1 , 0 , -1};
12 struct data {
13     int x , y;
14 };
15 
16 void init() {
17     memset(ok , false , sizeof(ok));
18 }
19 
20 bool judge(int x , int y) {              //判断点是否是‘.‘   且未经过
21     if(x < n && y < m && x >= 0 && y >= 0 && map[x][y] != ‘*‘ && !ok[x][y]) {
22         return true;
23     }
24     return false;
25 }
26 
27 bool judge2(int x , int y) {            //判断点是否是‘*‘
28     if(x < n && y < m && x >= 0 && y >= 0 && map[x][y] == ‘*‘) {
29         return true;
30     }
31     return false;
32 }
33 
34 int get(int x , int y) {     //壁画的相加
35     int num = 0;
36     for(int i = 0 ; i < 4 ; i++) {
37         if(judge2(x + tx[i] , y + ty[i])) {
38             num++;
39         }
40     }
41     return num;
42 }
43 
44 void bfs(int x , int y) {
45     vector<data > v;    //用来存相连的‘.‘
46     queue <data> Q;
47     data a;
48     a.x = x , a.y = y;
49     Q.push(a);
50     while(!Q.empty()) {
51         data temp = Q.front();
52         v.push_back(temp);
53         Q.pop();
54         if(map[temp.x][temp.y] == ‘.‘) {
55             res += get(temp.x , temp.y);
56             ok[temp.x][temp.y] = true;
57         }
58         for(int i = 0 ; i < 4 ; i++) {
59             a.x = temp.x + tx[i] , a.y = temp.y + ty[i];
60             if(judge(a.x , a.y)) {
61                 Q.push(a);
62                 ok[a.x][a.y] = true;
63             }
64         }
65     }
66     for(int i = 0 ; i < v.size() ; i++) {   
67         ans[v[i].x][v[i].y] = res;
68     }
69     v.clear();  //清空
70 }
71 
72 int main()
73 {
74     int q , sx , sy;
75     ios::sync_with_stdio(false);
76     while(cin >> n >> m >> q) {
77         memset(ans , 0 , sizeof(ans));
78         for(int i = 0 ; i < n ; i++) 
79             cin >> map[i];
80         init();
81         for(int i = 0 ; i < n ; i++) {
82             for(int j = 0 ; j < m ; j++) {
83                 res = 0;
84                 if(!ok[i][j] && map[i][j] == ‘.‘) {
85                     bfs(i , j);
86                 }
87             }
88         }
89         while(q--) {
90             cin >> sx >> sy;
91             cout << ans[sx - 1][sy - 1] << endl;
92         }
93     }
94 }