Problem p00189 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cmath>
#include <iostream>
#include <map>
#include <stdio.h>
#include <string.h>
#include <vector>
#define N 1000015
#define P pair<int, int>
#define ll long long
#define mk(a, b) make_pair(a, b)
#define mem(a, b) memset(a, b, sizeof(a))
using namespace std;
bool vis[10];
int dis[10];
int g[10][10];
int inf = 0x3f3f3f3f;
int n, sum;
void Dijkstra(int x) {
  mem(vis, false);
  mem(dis, inf);
  dis[x] = 0;
  // dis[1] = inf;
  for (int i = 0; i <= sum; ++i) {
    int MIN = inf, u = -1;
    for (int j = 0; j <= sum; ++j) {
      if (vis[j])
        continue;
      if (dis[j] < MIN) {
        MIN = dis[j];
        u = j;
      }
    }
    if (u == -1)
      return;
    vis[u] = true;
    for (int j = 0; j <= sum; ++j) {
      if (vis[j])
        continue;
      if (dis[j] > g[u][j] + MIN) {
        dis[j] = g[u][j] + MIN;
      }
    }
  }
}

int main() {

  ios::sync_with_stdio(false);
  while (cin >> n, n) {
    int s, e, c;
    mem(g, inf);
    sum = -1;
    for (int i = 0; i < n; ++i) {
      cin >> s >> e >> c;
      sum = max(s, sum);
      sum = max(e, sum);
      g[s][e] = g[e][s] = min(g[s][e], c);
    }
    int ans_n, ans_v = inf;
    for (int i = 0; i <= sum; ++i) {
      Dijkstra(i);
      int sum_temp = 0;
      for (int j = 0; j <= sum; ++j) {
        if (dis[j] == inf) {
          sum_temp = inf;
          break;
        }
        sum_temp += dis[j];
      }
      if (sum_temp < ans_v) {
        ans_v = sum_temp;
        ans_n = i;
      }
    }
    cout << ans_n << " " << ans_v << endl;
  }

  return 0;
}


Error: WA

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cmath>
#include <iostream>
#include <map>
#include <stdio.h>
#include <string.h>
#include <vector>
#define N 1000015
#define P pair<int, int>
#define ll long long
#define mk(a, b) make_pair(a, b)
#define mem(a, b) memset(a, b, sizeof(a))
using namespace std;
bool vis[10];
int dis[10];
int g[10][10];
int inf = 0x3f3f3f3f;
int n, sum;
void Dijkstra(int x) {
  mem(vis, false);
  mem(dis, inf);
  dis[x] = 0;
  // dis[1] = inf;
  for (int i = 0; i <= sum; ++i) {
    int MIN = inf, u = -1;
    for (int j = 0; j <= sum; ++j) {
      if (vis[j])
        continue;
      if (dis[j] < MIN) {
        MIN = dis[j];
        u = j;
      }
    }
    if (u == -1)
      return;
    vis[u] = true;
    for (int j = 0; j <= sum; ++j) {
      if (vis[j])
        continue;
      if (dis[j] > g[u][j] + MIN) {
        dis[j] = g[u][j] + MIN;
      }
    }
  }
}

int main() {
#ifndef ONLINE_JUDGE
  freopen("in.txt", "r", stdin);
#endif
  ios::sync_with_stdio(false);
  while (cin >> n, n) {
    int s, e, c;
    mem(g, inf);
    sum = -1;
    for (int i = 0; i < n; ++i) {
      cin >> s >> e >> c;
      sum = max(s, sum);
      sum = max(e, sum);
      g[s][e] = g[e][s] = min(g[s][e], c);
    }
    int ans_n, ans_v = inf;
    for (int i = 0; i <= sum; ++i) {
      Dijkstra(i);
      int sum_temp = 0;
      for (int j = 0; j <= sum; ++j) {
        if (dis[j] == inf) {
          sum_temp = inf;
          break;
        }
        sum_temp += dis[j];
      }
      if (sum_temp < ans_v) {
        ans_v = sum_temp;
        ans_n = i;
      }
    }
    cout << ans_n << " " << ans_v << endl;
  }

  return 0;
}