hdu 2389(最大匹配bfs版）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2389

思路：纯裸的一个最大匹配题，不过悲摧的是以前一直用的dfs版一直过不了,TLE无数次啊，然后改成bfs就过了。

  1 #include<iostream>

  2 #include<cstdio>

  3 #include<cstring>

  4 #include<algorithm>

  5 #include<vector>

  6 #include<cmath>

  7 #include<queue>

  8 using namespace std;

  9 #define MAXN 3333

 10 vector<int>map[MAXN];

 11 int ly[MAXN],lx[MAXN];

 12 int distx[MAXN],disty[MAXN];

 13 int n,m;

 14 struct Node {

 15     int x,y,s;

 16 } p[MAXN];

 17 struct Point {

 18     int x,y;

 19 } q[MAXN];

 20 

 21 bool bfs()

 22 {

 23     bool flag=false;

 24     memset(distx,0,(n+2)*sizeof(int));

 25     memset(disty,0,(n+2)*sizeof(int));

 26     queue<int>Q;

 27     for(int i=1; i<=n; i++) {

 28         if(lx[i]==-1)Q.push(i);

 29     }

 30     while(!Q.empty()) {

 31         int u=Q.front();

 32         Q.pop();

 33         for(int i=0; i<map[u].size(); i++) {

 34             int v=map[u][i];

 35             if(disty[v]==0) {

 36                 disty[v]=distx[u]+1;

 37                 if(ly[v]==-1)flag=true;

 38                 else {

 39                     distx[ly[v]]=disty[v]+1;

 40                     Q.push(ly[v]);

 41                 }

 42             }

 43         }

 44     }

 45     return flag;

 46 }

 47 

 48 int dfs(int u)

 49 {

 50     for(int i=0; i<map[u].size(); i++) {

 51         int v=map[u][i];

 52         if(disty[v]==distx[u]+1) {

 53             disty[v]=0;

 54             if(ly[v]==-1||dfs(ly[v])) {

 55                 ly[v]=u;

 56                 lx[u]=v;

 57                 return 1;

 58             }

 59         }

 60     }

 61     return 0;

 62 }

 63 

 64 

 65 int MaxMatch()

 66 {

 67     int res=0;

 68     memset(lx,-1,(n+2)*sizeof(lx[0]));

 69     memset(ly,-1,(n+2)*sizeof(ly[0]));

 70     while(bfs()) {

 71         for(int i=1; i<=n; i++) {

 72             if(lx[i]==-1)res+=dfs(i);

 73         }

 74     }

 75     return res;

 76 }

 77 

 78 int main()

 79 {

 80     //  freopen("1.txt","r",stdin);

 81     int _case,time,t=1;

 82     scanf("%d",&_case);

 83     while(_case--) {

 84         scanf("%d%d",&time,&n);

 85         for(int i=1; i<=n; i++)map[i].clear();

 86         for(int i=1; i<=n; i++) {

 87             scanf("%d%d%d",&p[i].x,&p[i].y,&p[i].s);

 88         }

 89         scanf("%d",&m);

 90         for(int i=1; i<=m; i++) {

 91             scanf("%d%d",&q[i].x,&q[i].y);

 92         }

 93         for(int i=1; i<=n; i++) {

 94             for(int j=1; j<=m; j++) {

 95                 double xx=(p[i].x-q[j].x)*(p[i].x-q[j].x)*1.0;

 96                 double yy=(p[i].y-q[j].y)*(p[i].y-q[j].y)*1.0;

 97                 double dd=sqrt(xx+yy);

 98                 if(dd<=1.0*time*p[i].s)map[i].push_back(j);

 99             }

100         }

101         int ans=MaxMatch();

102         printf("Scenario #%d:\n%d\n",t++,ans);

103         puts("");

104     }

105     return 0;

106 }

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