[bzoj4883][Lydsy2017年5月月赛]棋盘上的守卫

#include<iostream>
#include<cstdio>
#include<algorithm>
#define rint register int 
#define getchar() (*S++)
#define MN 100000
#define ll long long
char B[1<<26],*S=B;
using namespace std;
inline int read()
{
    int x = 0 , f = 1; char ch = getchar();
    while(ch < ‘0‘ || ch > ‘9‘){ if(ch == ‘-‘) f = -1;  ch = getchar();}
    while(ch >= ‘0‘ && ch <= ‘9‘){x = x * 10 + ch - ‘0‘;ch = getchar();}
    return x * f;
}

int n,m,cnt=0,fa[MN*2+5];
ll ans=0;
struct data{int x,c,r;}a[MN+5]; 
bool b[MN*2+5];
bool cmp(data a,data b){return a.x<b.x;}
inline int getfa(int x){return !fa[x]?x:fa[x]=getfa(fa[x]);}
int main()
{
    fread(B,1,1<<26,stdin);
    n=read();m=read();
    for(rint i=1;i<=n;++i)
        for(rint j=1;j<=m;++j)
            a[++cnt]=(data){read(),i,j+n};
    sort(a+1,a+cnt+1,cmp); 
    for(rint i=1;i<=cnt;++i)
    {
        int x=getfa(a[i].c),y=getfa(a[i].r);
        if(!(b[x]&b[y]))
        {
            if(x!=y)
                fa[x]=y,b[y]|=b[x];
            else b[x]=1;
            ans+=a[i].x;
        }    
    }
    printf("%lld\n",ans);
    return 0;
}