P1129 [ZJOI2007] bipartite graph matching game matrix

Thinking: Brain + bipartite graph matching 

Submissions: 1 (talked about in class)

answer:

Found: if they meet the meaning of the questions, then the rows and columns must be the one to one matched (requirement), the maximum matching must be $ n $.

We found that, by the way will be able to exchange the ranks will (appear to) have the greatest match staggered, converted into a state consistent with the meaning of the questions.

So the maximum match is $ n $ is the basis to judge.

 

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#define R register int
using namespace std;
#define ull unsigned long long
#define ll long long
#define pause (for(R i=1;i<=10000000000;++i))
#define IN freopen("NOIPAK++.in","r",stdin)
#define OUT freopen("out.out","w",stdout)
namespace Fread {
    static char B[1<<15],*S=B,*D=B;
#ifndef JACK
    #define getchar() (S==D&&(D=(S=B)+fread(B,1,1<<15,stdin),S==D)?EOF:*S++)
#endif
    inline int g() {
        R ret=0,fix=1; register char ch; while(!isdigit(ch=getchar())) fix=ch=='-'?-1:fix;
        do ret=ret*10+(ch^48); while(isdigit(ch=getchar())); return ret*fix;
    } inline bool isempty(const char& ch) {return ch<=36||ch>=127;}
    inline void gs(char* s) {register char ch; while(isempty(ch=getchar())); do *s++=ch; while(!isempty(ch=getchar()));}
}using Fread::g; using Fread::gs;
const int N=210;
int vis[N],pre[N],t,ans,n,tim; 
bool e[N][N];
inline bool dfs(int u) {
    for(R v=1;v<=n;++v) if(e[u][v]&&vis[v]!=tim) {
        vis[v]=tim; if(!pre[v]||dfs(pre[v])) {pre[v]=u; return true ;}
    } return false;
}
signed main() {
#ifdef JACK
#endif
    t=g(); while(t--) { ans=0,tim=0;
        memset(vis,0,sizeof(vis)),memset(pre,0,sizeof(pre)),memset(e,false,sizeof(e));
        n=g(); for(R i=1;i<=n;++i) for(R j=1;j<=n;++j) e[i][j]=g();
        for(R i=1;i<=n;++i) ++tim,ans+=dfs(i);
        if(ans==n) printf("Yes\n");
        else printf("No\n");
    }
}

---

2019.07.18