首页 > 代码库 > POJ 2421 Constructing Roads
POJ 2421 Constructing Roads
Language: Constructing Roads
Description There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two village A and B are connected, if and only if there is a road between A and B, or there exists a village C such that there is a road between A and C, and C and B are connected. We know that there are already some roads between some villages and your job is the build some roads such that all the villages are connect and the length of all the roads built is minimum. Input The first line is an integer N (3 <= N <= 100), which is the number of villages. Then come N lines, the i-th of which contains N integers, and the j-th of these N integers is the distance (the distance should be an integer within [1, 1000]) between village i and village j. Then there is an integer Q (0 <= Q <= N * (N + 1) / 2). Then come Q lines, each line contains two integers a and b (1 <= a < b <= N), which means the road between village a and village b has been built. Output You should output a line contains an integer, which is the length of all the roads to be built such that all the villages are connected, and this value is minimum. Sample Input 30 990 692990 0 179692 179 011 2 Sample Output 179 |
思路：裸地MST，只是他给出你有几条道路已经建好，只需要将建好的道路赋值为0即可
#include<cstdio>#include<iostream>#include<algorithm>#define MAXM 2000001#define MAXN 201using namespace std;struct node { int x,y; int val;};node a[MAXM];int map[MAXN][MAXN];int fa[MAXN],n,m,cnt,tot,sum;inline void read(int&x) { x=0;int f=1;char c=getchar(); while(c>‘9‘||c<‘0‘) {if(c==‘-‘) f=-1;c=getchar();} while(c>=‘0‘&&c<=‘9‘) {x=(x<<1)+(x<<3)+c-48;c=getchar();} x=x*f;}inline bool cmp(node x,node y) { return x.val<y.val;}inline int find(int x) { if(x==fa[x]) return x; else return fa[x]=find(fa[x]);}inline void kurskal() { sort(a+1,a+cnt+1,cmp); for(int i=1;i<=cnt;i++) { int xx=find(a[i].x); int yy=find(a[i].y); if(xx!=yy) { fa[xx]=yy; tot++; sum+=a[i].val; } if(tot==n-1) return; } }int main() { read(n); for(int i=1;i<=n;i++) fa[i]=i; for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) { read(map[i][j]); if(i==j) map[i][j]=1e8; } read(m); int x,y; for(int i=1;i<=m;i++) { read(x);read(y); map[x][y]=0; map[y][x]=0; } for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) { a[++cnt].x=i; a[cnt].y=j; a[cnt].val=map[i][j]; } kurskal(); printf("%d\n",sum); return 0;}
POJ 2421 Constructing Roads
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。