hdu 3722 Card Game 夜

http://acm.hdu.edu.cn/showproblem.php?pid=3722

KM  先求出任意两个字符串前后匹配的值 然后KM求最大匹配

越来越发现 图论题的关键在于建图呀

代码：

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<vector>
#include<set>
#include<queue>
#include<map>
#include<string>
#include <iomanip>
using namespace std;
const int INF=0x3f3f3f3f;
const int N=205;
const int M=1005;
char stmp[N][M];
int L[N];
int dist[N][N];
int f[N];
bool lv[N],rv[N];
int a[N],b[N];
bool dfs(int x,int n)
{
    lv[x]=true;
    for(int i=1;i<=n;++i)
    {
        if(!rv[i]&&a[x]+b[i]==dist[x][i])
        {
            rv[i]=true;
            if(f[i]==-1||dfs(f[i],n))
            {
                f[i]=x;
                return true;
            }
        }
    }
    return false;
}
int Km(int n)
{
    memset(f,-1,sizeof(f));
    memset(b,0,sizeof(b));
    for(int i=1;i<=n;++i)
    {
        a[i]=-1;
        for(int j=1;j<=n;++j)
        a[i]=max(a[i],dist[i][j]);
    }
    for(int l=1;l<=n;++l)
    {
        while(true)
        {
            memset(lv,false,sizeof(lv));
            memset(rv,false,sizeof(rv));
            if(dfs(l,n))
            break;
            int d=INF;
            for(int i=1;i<=n;++i)
            {
                if(lv[i])
                for(int j=1;j<=n;++j)
                {
                    if(!rv[j])
                    d=min(d,a[i]+b[j]-dist[i][j]);
                }
            }
            for(int i=1;i<=n;++i)
            {
                if(lv[i])
                a[i]-=d;
                if(rv[i])
                b[i]+=d;
            }
        }
    }
    int ans=0;
    for(int i=1;i<=n;++i)
    {
        if(f[i]!=-1)
        ans+=dist[f[i]][i];
    }
    return ans;
}
int main()
{
    //freopen("data.txt","r",stdin);
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        getchar();
        for(int i=1;i<=n;++i)
        {gets(stmp[i]);L[i]=strlen(stmp[i]);}
        memset(dist,0,sizeof(dist));
        for(int i=1;i<=n;++i)
        {
            for(int j=1;j<=n;++j)
            {
                if(i==j)
                continue;
                int l1=L[i]-1;
                int l2=0;
                for(;l1>=0&&l2<L[j];--l1,++l2)
                {
                    if(stmp[i][l1]!=stmp[j][l2])
                    break;
                }
                dist[i][j]=l2;
            }
        }
        printf("%d\n",Km(n));
    }
    return 0;
}