zoukankan      html  css  js  c++  java
  • zoj 2966 Build The Electric System 最小生成树

    Escape Time II

    Time Limit: 20 Sec  Memory Limit: 256 MB

    题目连接

    http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2966

    Description

    In last winter, there was a big snow storm in South China. The electric system was damaged seriously. Lots of power lines were broken and lots of villages lost contact with the main power grid. The government wants to reconstruct the electric system as soon as possible. So, as a professional programmer, you are asked to write a program to calculate the minimum cost to reconstruct the power lines to make sure there's at least one way between every two villages.

    Input

    Standard input will contain multiple test cases. The first line of the input is a single integer T (1 <= T <= 50) which is the number of test cases. And it will be followed by T consecutive test cases.

    In each test case, the first line contains two positive integers N and E (2 <= N <= 500, N <= E <= N * (N - 1) / 2), representing the number of the villages and the number of the original power lines between villages. There follow E lines, and each of them contains three integers, A, B, K (0 <= A, B < N, 0 <= K < 1000). A and B respectively means the index of the starting village and ending village of the power line. If K is 0, it means this line still works fine after the snow storm. If K is a positive integer, it means this line will cost K to reconstruct. There will be at most one line between any two villages, and there will not be any line from one village to itself.

    Output

    For each test case in the input, there's only one line that contains the minimum cost to recover the electric system to make sure that there's at least one way between every two villages.

    Sample Input

    1
    3 3
    0 1 5
    0 2 0
    1 2 9
    

    Sample Output

    5

    HINT

    题意

    给你个无向边带权图,让你输出最小生成树

    题解:

    Kruskal or prim

    代码:

    //qscqesze
    #include <cstdio>
    #include <cmath>
    #include <cstring>
    #include <ctime>
    #include <iostream>
    #include <algorithm>
    #include <set>
    #include <vector>
    #include <sstream>
    #include <queue>
    #include <typeinfo>
    #include <fstream>
    #include <map>
    #include <stack>
    typedef long long ll;
    using namespace std;
    //freopen("D.in","r",stdin);
    //freopen("D.out","w",stdout);
    #define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
    #define test freopen("test.txt","r",stdin)  
    #define maxn 200001
    #define mod 10007
    #define eps 1e-9
    int Num;
    char CH[20];
    //const int inf=0x7fffffff;   //нчоч╢С
    const int inf=0x3f3f3f3f;
    inline ll read()
    {
        ll 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;
    }
    inline void P(int x)
    {
        Num=0;if(!x){putchar('0');puts("");return;}
        while(x>0)CH[++Num]=x%10,x/=10;
        while(Num)putchar(CH[Num--]+48);
        puts("");
    }
    //**************************************************************************************
    
    
    int u[maxn],v[maxn],w[maxn],r[maxn];
    int pa[maxn],n,m;
    bool cmp(int i,int j)
    {
        return w[i]<w[j];
    }
    int fi(int x)
    {
        return pa[x]==x?x:pa[x]=fi(pa[x]);
    }
    int kruskal()
    {
        int ans=0;
        for(int i=0;i<n;i++)
            pa[i]=i;
        for(int i=0;i<m;i++)
            r[i]=i;
        sort(r,r+m,cmp);
        for(int i=0;i<m;i++)
        {
            int e=r[i];
            int x=fi(u[e]);
            int y=fi(v[e]);
            if(x!=y)
                ans+=w[e],pa[x]=y;
        }
        return ans;
    }
    int main()
    {
        //test;
        int t=read();
        while(t--)
        {
            n=read(),m=read();
            for(int i=0;i<m;i++)
            {
                int a=read(),b=read(),c=read();
                u[i]=a,v[i]=b,w[i]=c;
            }
            printf("%d
    ",kruskal());
        }
    }
  • 相关阅读:
    python+requests+excel 接口测试
    Pycharm配置git
    ubuntu16.04+ROS安装kinectV1
    ubuntu16.04安装有道词典
    ROS kinetic语音识别
    在Ubuntu16.04中python环境下实现tab键补全
    ros kinetic安装rbx1
    ubuntu14.04安装opencv3.1
    ubuntu16.04SSH无法连接
    VC6中函数点go to definition报告the symbol XXX is undefined
  • 原文地址:https://www.cnblogs.com/qscqesze/p/4540149.html
Copyright © 2011-2022 走看看