hdu 1102 Constructing Roads +1879 继续畅通工程（MST）

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1102

思路：

过该路已经建好，直接把边权值修改为0即可。

这题用Prim和kruskal算法都能过。

hdu 1102：

#include<stdio.h>#include<iostream>#include<string>#include<string.h>#include<algorithm>#include<vector>#include<time.h>#include<queue>#include<stack>#include<iterator>#include<math.h>#include<stdlib.h>#include<limits.h>#include<memory.h>//#define ONLINE_JUDGE#define eps 1e-8#define INF 0x7fffffff#define FOR(i,a) for((i)=0;i<(a);(i)++)                          //[i,a);#define MEM(a) (memset((a),0,sizeof(a)))#define sfs(a) scanf("%s",a)#define sf(a) scanf("%d",&a)#define sfI(a) scanf("%I64d",&a)#define pf(a) printf("%d\n",a)#define pfI(a) printf("%I64d\n",a)#define pfs(a) printf("%s\n",a)#define sfd(a,b) scanf("%d%d",&a,&b)#define sft(a,b,c)scanf("%d%d%d",&a,&b,&c)#define for1(i,a,b) for(int i=(a);i<b;i++)#define for2(i,a,b) for(int i=(a);i<=b;i++)#define for3(i,a,b)for(int i=(b);i>=a;i--)#define MEM1(a) memset(a,0,sizeof(a))#define MEM2(a) memset(a,-1,sizeof(a))#define LL __int64const double PI = acos(-1.0);template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }template<class T> inline T Min(T a, T b) { return a < b ? a : b; }template<class T> inline T Max(T a, T b) { return a > b ? a : b; }using namespace std;template<class T>T Mint(T a, T b, T c) {    if (a>b) {        if (c>b)            return b;        return c;    }    if (c>a)        return a;    return c;}template<class T>T Maxt(T a, T b, T c) {    if (a>b) {        if (c>a)            return c;        return a;    }    else if (c > b)        return c;    return b;}const int maxn=105;int T,n,m;int a,b,c,pos;int ans,cnt;int map[maxn][maxn],low[maxn];bool vis[maxn];int Prim(){    MEM1(vis);    int ans=0;    vis[1]=1;pos=1;    for(int i=1;i<=n;i++){        if(i!=pos)            low[i]=map[pos][i];    }    for(int i=1;i<n;i++){        int min=INT_MAX;        for(int j=1;j<=n;j++){            if(!vis[j]&low[j]<min){                    min=low[j];                    pos=j;            }        }        vis[pos]=1;        for(int j=1;j<=n;j++){            if(!vis[j]&&low[j]>map[pos][j])                low[j]=map[pos][j];        }        ans+=min;    }    return ans;}int main(){#ifndef ONLINE_JUDGE    freopen("test.in","r",stdin);    freopen("test.out","w",stdout);#endif    while(~sf(n)){        for2(i,1,n){            for2(j,1,n){                sf(map[i][j]);            }        }        sf(m);        for1(i,0,m){            sfd(a,b);            map[a][b]=map[b][a]=0;        }        ans=Prim();        pf(ans);    }    return 0;}

hdu 1879：

#include <limits.h>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <time.h>#include <algorithm>#include <iostream>#include <iterator>#include <sstream>#include <queue>#include <stack>#include <string>#include <vector>#include <set>//#define ONLINE_JUDGE#define eps 1e-6#define INF 0x7fffffff                                          //INT_MAX#define inf 0x3f3f3f3f                                          //int??????????????????#define FOR(i,a) for((i)=0;i<(a);(i)++)                          //[i,a);#define MEM(a) (memset((a),0,sizeof(a)))#define sfs(a) scanf("%s",a)#define sf(a) scanf("%d",&a)#define sfI(a) scanf("%I64d",&a)#define pf(a) printf("%d\n",a)#define pfI(a) printf("%I64d\n",a)#define pfs(a) printf("%s\n",a)#define sfd(a,b) scanf("%d%d",&a,&b)#define sft(a,b,c)scanf("%d%d%d",&a,&b,&c)#define for1(i,a,b) for(int i=(a);i<b;i++)#define for2(i,a,b) for(int i=(a);i<=b;i++)#define for3(i,a,b)for(int i=(b);i>=a;i--)#define MEM1(a) memset(a,0,sizeof(a))#define MEM2(a) memset(a,-1,sizeof(a))#define MEM3(a) memset(a,0x3f,sizeof(a))#define MEMS(a) memset(a,'\0',sizeof(a))#define LL __int64const double PI = acos(-1.0);template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }template<class T> inline T Min(T a, T b) { return a < b ? a : b; }template<class T> inline T Max(T a, T b) { return a > b ? a : b; }using namespace std;template<class T>T Mint(T a, T b, T c) {    if (a>b) {        if (c>b)            return b;        return c;    }    if (c>a)        return a;    return c;}template<class T>T Maxt(T a, T b, T c) {    if (a>b) {        if (c>a)            return c;        return a;    }    else if (c > b)        return c;    return b;}const int maxn = 105;int T, n, m;int map[maxn][maxn];bool vis[maxn];//标记数组int low[maxn];//i点到邻近点（未标记）的最小距离int a,b,c,d;int Prim(){    int ans=0,pos,min;    MEM1(vis);    //从某点开始，分别标记和记录该点    vis[1]=1;pos=1;    //第一次给low[]赋值    for2(i,1,n){        if(i!=pos)            low[i]=map[pos][i];    }    for1(i,1,n){//找最小值并记录位置        min=INT_MAX;        for2(j,1,n){            if(!vis[j]&&min>low[j]){                min=low[j];                pos=j;            }        }        ans+=min;        vis[pos]=1;        for2(j,1,n){            if(!vis[j]&&low[j]>map[pos][j])                low[j]=map[pos][j];        }    }    return ans;}int main() {#ifndef ONLINE_JUDGE    freopen("test.in","r",stdin);    freopen("test.out","w",stdout);#endif    while(~sf(n)&&n){        int num=n*(n-1)/2;        for2(i,1,num){            scanf("%d%d%d%d",&a,&b,&c,&d);            if(d==0) map[a][b]=map[b][a]=c;            else map[a][b]=map[b][a]=0;        }        int ans=Prim();        pf(ans);    }    return 0;}

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