学步园

Description

Input

Output

Sample Input

Sample Output

我完全不知道这题在讲什么……不就是网络流吗……为什么讲这么多

A是源Z是汇，跑一遍网络流乱搞就AC了

#include<cstdio>
#include<iostream>
#include<cstring>
#define S 1
#define T 26
#define inf 0x7fffffff
using namespace std;
struct edge{
	int to,next,v;
}e[50001];
int n,cnt=1,ans;
int head[10001];
int h[10001];
int q[10001];
inline void ins(int u,int v,int w)
{
	e[++cnt].v=w;
	e[cnt].to=v;
	e[cnt].next=head[u];
	head[u]=cnt;
}
inline void insert(int u,int v,int w)
{
	ins(u,v,w);
	ins(v,u,0);
}inline bool bfs()  
{  
    memset(h,-1,sizeof(h));  
    int t=0,w=1;  
    q[1]=S;h[S]=0;  
    while (t<w)  
    {  
        int now=q[++t];  
        for (int j=head[now];j;j=e[j].next)  
        {  
            if (e[j].v&&h[e[j].to]==-1)  
            {  
                q[++w]=e[j].to;  
                h[e[j].to]=h[now]+1;  
            }  
        }  
    }  
    if (h[T]==-1) return 0;  
    return 1;  
}  
inline int dfs(int x,int f)  
{  
    if (x==T||f==0) return f;  
    int w,used=0;  
    for (int i=head[x];i;i=e[i].next)  
    {  
        if (e[i].v&&h[e[i].to]==h[x]+1)  
        {  
            w=used;  
            w=dfs(e[i].to,min(e[i].v,f-used));  
            e[i].v-=w;  
            e[i^1].v+=w;  
            used+=w;  
            if (used==f) return f;  
        }  
    }  
    if (!used) h[x]==-1;  
    return used;  
}  
inline void dinic()  
{while (bfs()) ans+=dfs(S,inf);}  
int main()
{
	cin>>n;
	for (int i=1;i<=n;i++)
	{
		char a,b;
		int c;
		cin>>a>>b>>c;
		insert(a-'A'+1,b-'A'+1,c);
	}
	dinic();
	cout<<ans;
}