Submission #770062

#	Time	Username	Problem	Language	Result	Execution time	Memory
770062		mgl_diamond	Robot (JOI21_ho_t4)	C++17	0 / 100	3046 ms	37436 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);
  }
}

struct edge {
  int u, v, c, p;
  edge (int _u=0, int _v=0, int _c=0, int _p=0) : u(_u), v(_v), c(_c), p(_p) {}
  int oth(int node) { return node ^ u ^ v; }
};

struct state {
  int cost, u, need, i;
  state(int _c=0, int _u=0, int _i=0, int _need=0) : cost(_c), u(_u), i(_i), need(_need) {}
  friend bool operator < (const state &a, const state &b) {
    return a.cost > b.cost;
  }
};

const ll LINF = 1e15;
const int N = 1e5+5;
const int M = 2e5+5;

int n, m;
ll sum[M];
edge e[M];
vector<int> graph[N];
vector<ll> dp[N][2];

int get(int u, int i) {
  return lower_bound(all(graph[u]), i) - graph[u].begin();
}

int main() {
  setIO("");

  cin >> n >> m;

  foru(i, 1, m) {
    int u, v, c, p;
    cin >> u >> v >> c >> p;
    e[i] = edge(u, v, c, p);
    graph[u].push_back(i);
    graph[v].push_back(i);
  }

  foru(i, 1, n) {
    dp[i][0].resize(sz(graph[i]), LINF);
    dp[i][1].resize(sz(graph[i]), LINF);
  }

  priority_queue<state> pq;
  pq.push(state(0, 1, -1, -1));

  while (!pq.empty()) {
    state at = pq.top(); pq.pop();
    int u = at.u, lst = at.i, need = at.need;
    if (lst != -1 && dp[u][need][lst] != at.cost) continue;
    // cout << at.cost << " " << u << " " << lst << " " << need << "\n";

    foru(i, 0, sz(graph[u])-1) {
      if (i==lst && need) continue;
      int idx = graph[u][i];
      sum[e[idx].c] += e[idx].p;
    }

    foru(i, 0, sz(graph[u])-1) {
      if (i == at.i) continue;
      int idx = graph[u][i];
      int v = e[idx].oth(u);
      int kth = get(v, idx);
      ll cost;
      
      // we change color of edge idx
      cost = at.cost + e[idx].p;
      if (dp[v][1][kth] > cost) {
        dp[v][1][kth] = cost;
        pq.push(state(cost, v, kth, 1));
      }

      // we change color of its neighbor
      cost = at.cost + sum[e[idx].c] - e[idx].p;
      if (dp[v][0][kth] > cost) {
        dp[v][0][kth] = cost;
        pq.push(state(cost, v, kth, 0));
      }
    }

    foru(i, 0, sz(graph[u])-1) {
      int idx = graph[u][i];
      sum[e[idx].c] = 0;
    }
  }

  ll ans = LINF;
  foru(i, 0, sz(graph[n])-1) ans = min(ans, min(dp[n][0][i], dp[n][1][i]));
  cout << (ans == LINF ? -1 : ans);
}

Compilation message (stderr)

Main.cpp: In constructor 'state::state(int, int, int, int)':
Main.cpp:30:22: warning: 'state::i' will be initialized after [-Wreorder]
   30 |   int cost, u, need, i;
      |                      ^
Main.cpp:30:16: warning:   'int state::need' [-Wreorder]
   30 |   int cost, u, need, i;
      |                ^~~~
Main.cpp:31:3: warning:   when initialized here [-Wreorder]
   31 |   state(int _c=0, int _u=0, int _i=0, int _need=0) : cost(_c), u(_u), i(_i), need(_need) {}
      |   ^~~~~
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: 0 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42