Flowery Trails

input/code.cpp: In function 'int main()':
input/code.cpp:33:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0; j < v[i].size(); ++j) {
                                   ^

#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
using namespace std;
#define F first
#define S second
int d[10000], d2[10000], L[250000];
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> v[n];
  vector<int> uid[n];
  set<int> g[n];
  for (int i = 0; i < m; ++i) {
    int a, b, l;
    cin >> a >> b >> l;
    v[--a].push_back({--b, l});
    v[b].push_back({a, l});
    uid[a].push_back(i);
    uid[b].push_back(i);
    L[i] = l;
  }
  for (int i = 0; i < n; ++i) d[i] = 1e9, d2[i] = 1e9;
  priority_queue<pair<int, int>> q;
  q.push({0, 0});
  d[0] = 0;
  while (!q.empty()) {
    int i = q.top().S;
    q.pop();
    for (int j = 0; j < v[i].size(); ++j) {
      pair<int, int> p = v[i][j];
      if (d[i]+p.S < d[p.F]) {
        d[p.F] = d[i]+p.S;
        q.push({-d[p.F], p.F});
        g[p.F].clear();
        g[p.F].insert(uid[i][j]);
      } else if (d[i]+p.S == d[p.F]) g[p.F].insert(uid[i][j]);
    }
  }
  long sum = 0;
  set<int> chosen;
  q = priority_queue<pair<int, int>>();
  q.push({0, n-1});
  d2[n-1] = 0;
  while (!q.empty()) {
    int i = q.top().S;
    q.pop();
    if (d[i]+d2[i] == d[n-1]) {
      for (int ge : g[i]) {
        chosen.insert(ge);
      }
    }
    for (pair<int, int> p : v[i]) {
      if (d2[i]+p.S < d2[p.F]) {
        d2[p.F] = d2[i]+p.S;
        q.push({-d2[p.F], p.F});
      }
    }
  }
  for (int i : chosen) {
    sum += L[i];
  }
  cout << sum*2 << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED