2 条题解
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1
#include<iostream> #include<fstream> #include<iomanip> #include<stdio.h> #include<cstdio> #include<math.h> #include<cmath> #include<algorithm> #include<string> #include<cstring> #include<string.h> #include<vector> #include<stack> #include<queue> #include<map> #include<set> #include<cstdlib> #include<stdlib.h> #include<ctime> #include<time.h> using namespace std; #define LL long long const int N=1e5+5; const LL INF=0x3f3f3fff3f3f3f; struct node{ LL x,y,z; }p[N],t[N]; LL fa[N],len,n,m; void init(){ for(int i=0;i<=n;i++){ fa[i]=i; } } bool cmp(node a,node b){ if(a.z!=b.z){ return a.z<b.z; } if(a.x!=b.x){ return a.x<b.x; } return a.y<b.y; } int find(int x){ if(fa[x]==x){ return x; } fa[x]=find(fa[x]); return fa[x]; } LL kruskal1(){ LL num=0,sum=0; for(int i=0;i<m;i++){ int x=p[i].x; int y=p[i].y; x=find(x); y=find(y); if(x!=y){ fa[x]=y; num++; t[len].x=p[i].x; t[len].y=p[i].y; t[len].z=p[i].z; len++; sum+=p[i].z; if(num==n-1){ return sum; } } } return INF; } LL kruskal2(LL xx,LL yy,LL zz){ LL num=0,sum=0; for(int i=0;i<m;i++){ LL x=p[i].x; LL y=p[i].y; if(xx==x&&yy==y){ continue; } x=find(x); y=find(y); if(x!=y){ fa[x]=y; num++; sum+=p[i].z; if(num==n-1){ return sum; } } } return INF; } int main(){ /* freopen(".in","r",stdin); freopen(".out","w",stdout); */ cin>>n>>m; init(); for(int i=0;i<m;i++){ cin>>p[i].x>>p[i].y>>p[i].z; if(p[i].x>p[i].y){ swap(p[i].x,p[i].y); } } sort(p,p+m,cmp); LL ans=kruskal1(); LL sum=INF; for(int i=0;i<len;i++){ init(); LL num=kruskal2(t[i].x,t[i].y,t[i].z); if(num<sum&&num>ans){ sum=num; } } cout<<sum<<endl; return 0; }
信息
- ID
- 407
- 时间
- 1000ms
- 内存
- 256MiB
- 难度
- 7
- 标签
- 递交数
- 81
- 已通过
- 21
- 上传者