You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
46 lines
1.4 KiB
46 lines
1.4 KiB
#include <bits/stdc++.h>
|
|
using namespace std;
|
|
#define int long long
|
|
#define endl "\n"
|
|
const int INF = 0x3f3f3f3f;
|
|
const int N = 110;
|
|
|
|
int mp[N][N], dis[N][N];
|
|
int n, m, a, b, c, ans;
|
|
|
|
void floyd() {
|
|
for (int k = 1; k <= n; k++) {
|
|
for (int i = 1; i < k; i++) // 枚举ij
|
|
for (int j = i + 1; j < k; j++) // 注意ijk不能相同
|
|
if (ans > mp[i][j] + dis[j][k] + dis[k][i])
|
|
ans = mp[i][j] + dis[j][k] + dis[k][i];
|
|
|
|
for (int i = 1; i <= n; i++) // 原floyd
|
|
for (int j = 1; j <= n; j++)
|
|
if (mp[i][j] > mp[i][k] + mp[k][j])
|
|
mp[i][j] = mp[i][k] + mp[k][j];
|
|
}
|
|
}
|
|
signed main() {
|
|
while (cin >> n >> m && (~n && ~m)) {
|
|
for (int i = 1; i <= n; i++)
|
|
for (int j = 1; j <= n; j++)
|
|
if (i == j)
|
|
mp[i][j] = dis[i][j] = 0;
|
|
else
|
|
mp[i][j] = dis[i][j] = INF;
|
|
while (m--) {
|
|
cin >> a >> b >> c;
|
|
if (c < mp[a][b]) // 防重边，怕了怕了
|
|
mp[a][b] = dis[a][b] = c;
|
|
if (c < mp[b][a])
|
|
mp[b][a] = dis[b][a] = c;
|
|
}
|
|
ans = INF;
|
|
floyd();
|
|
if (ans == INF)
|
|
puts("It's impossible.");
|
|
else
|
|
printf("%lld\n", ans);
|
|
}
|
|
} |