标签：style blog http color io os ar java for
Cows are such finicky eaters. Each cow has a preference for certain foods and drinks, and she will consume no others.
Farmer John has cooked fabulous meals for his cows, but he forgot to check his menu against their preferences. Although he might not be able to stuff everybody, he wants to give a complete meal of both food and drink to as many cows as possible.
Farmer John has cooked F (1 ≤ F ≤ 100) types of foods and prepared D (1 ≤ D ≤ 100) types of drinks. Each of his N (1 ≤ N ≤ 100) cows has decided whether she is willing to eat a particular food or drink a particular drink. Farmer John must assign a food type and a drink type to each cow to maximize the number of cows who get both.
Each dish or drink can only be consumed by one cow (i.e., once food type 2 is assigned to a cow, no other cow can be assigned food type 2).
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1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cmath> 5 #include <algorithm> 6 #include <climits> 7 #include <vector> 8 #include <queue> 9 #include <cstdlib> 10 #include <string> 11 #include <set> 12 #include <stack> 13 #define LL long long 14 #define pii pair<int,int> 15 #define INF 0x3f3f3f3f 16 using namespace std; 17 const int maxn = 500; 18 struct arc{ 19 int to,flow,next; 20 arc(int x = 0,int y = 0,int z = -1){ 21 to = x; 22 flow = y; 23 next = z; 24 } 25 }; 26 arc e[200000]; 27 int head[maxn],d[maxn],cur[maxn]; 28 int tot,N,F,D,s,t; 29 void add(int u,int v,int flow){ 30 e[tot] = arc(v,flow,head[u]); 31 head[u] = tot++; 32 e[tot] = arc(u,0,head[v]); 33 head[v] = tot++; 34 } 35 bool bfs(){ 36 memset(d,-1,sizeof(d)); 37 queue<int>q; 38 d[s] = 1; 39 q.push(s); 40 while(!q.empty()){ 41 int u = q.front(); 42 q.pop(); 43 for(int i = head[u]; ~i; i = e[i].next){ 44 if(e[i].flow && d[e[i].to] == -1){ 45 d[e[i].to] = d[u] + 1; 46 q.push(e[i].to); 47 } 48 } 49 } 50 return d[t] > -1; 51 } 52 int dfs(int u,int low){ 53 if(u == t) return low; 54 int tmp = 0,a; 55 for(int &i = cur[u]; ~i; i = e[i].next){ 56 if(e[i].flow && d[e[i].to] == d[u] + 1 &&(a=dfs(e[i].to,min(low,e[i].flow)))){ 57 e[i].flow -= a; 58 e[i^1].flow += a; 59 tmp += a; 60 low -= a; 61 if(!low) break; 62 } 63 } 64 if(!tmp) d[u] = -1; 65 return tmp; 66 } 67 int dinic(){ 68 int ans = 0; 69 while(bfs()){ 70 memcpy(cur,head,sizeof(head)); 71 ans += dfs(s,INF); 72 } 73 return ans; 74 } 75 int main() { 76 while(~scanf("%d %d %d",&N,&F,&D)){ 77 memset(head,-1,sizeof(head)); 78 s = tot = 0; 79 int n = F + D,a,b,c; 80 t = n + (N<<1|1); 81 for(int i = 1; i <= N; ++i){ 82 scanf("%d %d",&a,&b); 83 while(a--){ 84 scanf("%d",&c); 85 add(c,n+(i<<1)-1,1); 86 } 87 add(n+(i<<1)-1,n+(i<<1),1); 88 while(b--){ 89 scanf("%d",&c); 90 add(n+(i<<1),F+c,1); 91 } 92 } 93 for(int i = 1; i <= F; ++i) add(s,i,1); 94 for(int i = 1; i <= D; ++i) add(F+i,t,1); 95 printf("%d\n",dinic()); 96 } 97 return 0; 98 }
标签：style blog http color io os ar java for
原文地址：http://www.cnblogs.com/crackpotisback/p/4051490.html
