无向图最小环

ＬＣＡ＋最小生成树是错的

 

 

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<vector>
#define maxn 310
using namespace std;
const long long INF = 1e17;
int pos[maxn][maxn];
long long map[maxn][maxn];
long long dis[maxn][maxn];
vector<int>ins;
int get(int x, int y) {//神仙分治
	if (pos[x][y] == 0) return 0;
	get(x, pos[x][y]);
	ins.push_back(pos[x][y]);
	get(pos[x][y], y);
}
int main() {
	int n, m;
	for (int i = 0; i < maxn; i++) {
		for (int j = 0; j < maxn; j++) {
			map[i][j] = INF;
		}
	}
	scanf("%d %d", &n, &m);
	long long len;
	int be, en;
	for (int i = 1; i <= n; i++) map[i][i] = 0;
	for (int i = 0; i < m; i++){
		scanf("%d %d %lld", &be, &en, &len);
		map[be][en] = map[en][be] = min(map[be][en], len);
		
	}
	memcpy(dis, map, sizeof(map));
	long long ans = INF;
	for (int k = 1; k <= n; k++) {
		for (int i = 1; i < k; i++) {
			for (int j = i+1; j < k; j++) {
				if (ans > dis[i][j] + map[i][k] + map[k][j]) {
					ans = dis[i][j] + map[i][k] + map[k][j]; 
					ins.clear();
					ins.push_back(i);
					get(i, j);
					ins.push_back(j);
					ins.push_back(k);
				}
			}
		}
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				if (dis[i][j] > dis[i][k] + dis[k][j]) {
					pos[i][j] = k;
					dis[i][j] = dis[i][k] + dis[k][j];
				}
			}
		}
	}
	if (ans == INF) {
		printf("No solution.\n");
	}
	else {
		for (int i = 0; i < ins.size(); i++) {
			printf("%d ", ins[i]);
		}
		printf("\n");
	}
	return 0;
}