Submission #770355

#	Time	Username	Problem	Language	Result	Execution time	Memory
770355		mgl_diamond	Robot (JOI21_ho_t4)	C++17	100 / 100	763 ms	81004 KiB

Main

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
 
#define foru(i, l, r) for(int i=(l); i<=(r); ++i)
#define ford(i, l, r) for(int i=(l); i>=(r); --i)
#define fore(x, v) for(auto &x : v)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define fi first
#define se second
 
void setIO(string name) {
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  if (!name.empty()) {
    freopen((name + ".in").c_str(), "r", stdin);
    freopen((name + ".out").c_str(), "w", stdout);
  }
}
 
const ll LINF = 1e15;
const int N = 1e5+5;
const int M = 2e5+5;
 
int n, m;
map<int, vector<ii>> graph[N];
ll dp[N];
map<int, ll> dp2[N], sum[N];
 
int main() {
  setIO("");

  cin >> n >> m;

  foru(i, 1, m) {
    int u, v, c, p;
    cin >> u >> v >> c >> p;
    graph[u][c].emplace_back(v, p);
    graph[v][c].emplace_back(u, p);
    sum[u][c] += p;
    sum[v][c] += p;
  } 

  memset(dp, 0x3f, sizeof(dp));
  priority_queue<pair<ll, ii>> pq;
  dp[1] = 0;
  pq.push({0, {1, 0}});

  while (!pq.empty()) {
    auto top = pq.top(); pq.pop();

    ll cost = top.fi;
    int u = top.se.fi, c = top.se.se;

    if (!c) {
      if (-cost != dp[u]) continue;
      fore(nc, graph[u]) fore(info, nc.se) {
        int v = info.fi, p = info.se;
        ll ncost;

        ncost = sum[u][nc.fi] - p - cost;
        if (ncost < dp[v]) {
          dp[v] = ncost;
          pq.push({-ncost, {v, 0}});
        }

        ncost = p - cost;
        if (ncost < dp[v]) {
          dp[v] = ncost;
          pq.push({-ncost, {v, 0}});
        }

        ncost = -cost;
        if ((dp2[v].find(nc.fi) == dp2[v].end()) || ncost < dp2[v][nc.fi]) {
          dp2[v][nc.fi] = ncost;
          pq.push({-ncost, {v, nc.fi}});
        }
      }
    } 
    else {
      if (-cost != dp2[u][c]) continue;
      ll ncost = sum[u][c] - cost;
      fore(info, graph[u][c]) {
        int v = info.fi, p = info.se;
        if (ncost - p < dp[v]) {
          dp[v] = ncost - p;
          pq.push({-ncost + p, {v, 0}});
        }
      }
    }
  }

  cout << (dp[n] < LINF ? dp[n] : -1);
}

Compilation message (stderr)

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:18:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |     freopen((name + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:19:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |     freopen((name + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 34 / 34
• Subtask 2: 24 / 24
• Subtask 3: 42 / 42