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题目大意:
求一个最小环。
用Floyd 求最小环算法。
#include <iostream> #include <cstdlib> #include <cstdio> #include <algorithm> #include <vector> #include <queue> #include <cmath> #include <cstring> using namespace std; #define INF 0xfffffff #define maxn 260 int G[maxn][maxn], dist[maxn][maxn]; int Pre[maxn][maxn], Path[maxn]; int m, n, CrossNum = 0; void SearchPath(int Star,int End) { while(Star != End) { Path[CrossNum ++] = Star; Star = Pre[Star][End]; } Path[CrossNum ++] = Star; } void Floyd() { int MinLoop = INF; for(int k=1; k<=n; k++) { for(int i=1; i<k; i++) { for(int j=i+1; j<k; j++) { if( dist[i][j] + G[i][k] + G[k][j] < MinLoop ) { MinLoop = dist[i][j] + G[i][k] + G[k][j]; CrossNum = 0; SearchPath(i,j); Path[CrossNum++] = k; } } } for(int i=1; i<=n; i++) { for(int j=1; j<=n; j++) { if(dist[i][j] > dist[i][k] + dist[k][j]) { dist[i][j] = dist[i][k] + dist[k][j]; Pre[i][j] = Pre[i][k]; } } } } } void Init() { for(int i=1; i<=n; i++) { for(int j=1; j<=n; j++) { dist[i][j] = G[i][j] = INF; Pre[i][j] = j; CrossNum = 0; } } } int main() { while(cin >> n >> m) { Init(); for(int i=0; i<m; i++) { int a, b, c; cin >> a >> b >> c; G[a][b] = G[b][a] = dist[a][b] = dist[b][a] = min(dist[a][b], c); } Floyd(); if( CrossNum) { for(int i=0; i<CrossNum - 1; i++) { printf("%d ", Path[i]); } printf("%d\n", Path[CrossNum - 1]); } else cout <<"No solution." << endl; } return 0; }
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原文地址:http://www.cnblogs.com/chenchengxun/p/4176909.html