# hdu 1853 Cyclic Tour (有向环覆盖，拆点，二分图最佳匹配，KM算法)

Posted by 111qqz on Thursday, June 2, 2016

## TOC

hdu 1853 题目链接

``````/* ***********************************************
Author :111qqz
Created Time :2016年06月02日 星期四 20时13分25秒
File Name :code/hdu/1853.cpp
************************************************ */

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
#include <ctime>
#define fst first
#define sec second
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define ms(a,x) memset(a,x,sizeof(a))
typedef long long LL;
#define pi pair < int ,int >
#define MP make_pair

using namespace std;
const double eps = 1E-8;
const int dx4[4]={1,0,0,-1};
const int dy4[4]={0,-1,1,0};
const int inf = 0x3f3f3f3f;
const int N=205;
int n,m;
bool visx[N],visy[N];
int lx[N],ly[N];
int slk[N];
int w[N][N];

bool find( int u)
{
visx[u] = true;
for ( int v = 1 ; v <= n ; v++)
{
if (visy[v]) continue;
int tmp = lx[u] + ly[v] - w[u][v];
if (tmp==0)
{
visy[v] = true;

{
return true;
}
}else if (tmp<slk[v]) slk[v] = tmp;
}
return false;
}
int KM()
{
ms(lx,0xc0);
ms(ly,0);

for ( int i = 1 ; i <= n ; i++)
for ( int j = 1 ; j <= n ; j++)
lx[i] = max(lx[i],w[i][j]);
for ( int i = 1 ; i <= n ; i++) if (lx[i]==-inf-1) return -1; //?

for ( int i = 1 ; i <= n ; i++)
{
ms(slk,0x3f);

while (1)
{
ms(visx,false);
ms(visy,false);

if (find(i)) break;

int d = inf;

for ( int j = 1 ; j <= n ; j++)
if (!visy[j]&&slk[j]<d) d = slk[j];

for ( int j = 1 ; j <= n ; j++)
if (visx[j]) lx[j]-=d;
for ( int j = 1 ; j <= n ; j++)
if (visy[j]) ly[j]+=d ; else slk[j]-=d;
}
}
int res = 0 ;

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

return -res;

}
int main()
{
#ifndef  ONLINE_JUDGE
freopen("code/in.txt","r",stdin);
#endif

while (scanf("%d%d",&n,&m)!=EOF)
{
ms(w,0xc0);
for ( int i = 1 ; i <= m ; i++)
{
int u,v,cost;
scanf("%d%d%d",&u,&v,&cost);
w[u][v] =max(w[u][v],-cost); //会不会有重边。..果然有。
}

int ans = KM();
printf("%d\n",ans);

}

#ifndef ONLINE_JUDGE
fclose(stdin);
#endif
return 0;
}
``````

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