Zoj 2849 attack of panda virus (priority_queue)

Priority queue. It is said that the flag is a parallel query set. No idea. It seems that the priority queue is directly written in STL and forced me to use STL. Prioriry_queue is unfamiliar.

PS: the smaller the value, the higher the priority. Therefore, when the <operator is overloaded, It is sorted by priority from large to small.

bool operator < (const node a, const node b) {
if(a.day != b.day)    return a.day > b.day;
return a.type > b.type;
}

 

Refer to online code

View code

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <queue>
 5 
 6 using namespace std;
 7 
 8 const int N = 510;
 9 const int inf = ~0u>>2;
10 
11 struct node {
12     int x, y;
13     int day;
14     int type;
15 
16 };
17 
18 priority_queue<node> q;
19 
20 int dir[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
21 int m, n;
22 int mp[N][N];
23 int list[N*N];
24 
25 bool operator < (const node a, const node b) {
26         if(a.day != b.day)    return a.day > b.day;
27         return a.type > b.type;
28 }
29 
30 bool insq(int x, int y) {
31     if(x < 0 || x >= m || y < 0 || y >= n)    return false;
32     return true;
33 }
34 
35 void bfs() {
36     node u, v;
37     int d, i;
38 
39     while(!q.empty()) {
40         u = q.top(); q.pop();
41 
42         d = -inf;
43         v.day = u.day;
44         v.type = u.type;
45 
46         for(i = 0; i < 4; ++i) {
47             v.x = u.x + dir[i][0];
48             v.y = u.y + dir[i][1];
49 
50             if(!insq(v.x, v.y) || mp[v.x][v.y] > 0)    continue;
51 
52             if(-1*mp[v.x][v.y] <= v.day) {
53                 mp[v.x][v.y] = v.type;
54                 list[v.type]++;
55                 q.push(v);
56             } else if(mp[v.x][v.y] > d) {
57                 d = mp[v.x][v.y];
58             }
59         }
60         if(d != -inf) {
61             u.day = -1*d;
62             q.push(u);
63         }
64     }
65 }
66 
67 int main() {
68     freopen("data.in", "r", stdin);
69 
70     int i, j, t;
71     node p;
72     while(~scanf("%d%d", &m, &n)) {
73         memset(list, 0, sizeof(list));
74 
75         for(i = 0; i < m; ++i) {
76             for(j = 0; j < n; ++j) {
77                 scanf("%d", &mp[i][j]);
78                 if(mp[i][j] > 0) {
79                     p.x = i; p.y = j;
80                     p.day = 1; p.type = mp[i][j];
81                     list[p.type] ++;
82                     q.push(p);
83                 }
84             }
85         }
86         bfs();
87         scanf("%d", &t);
88         while(t--) {
89             scanf("%d", &i);
90             printf("%d\n", list[i]);
91         }
92     }
93     return 0;
94 }