CODE THANKS FESTIVAL 2015 G: カメレオン

問題

code-thanks-festival-2015-open.contest.atcoder.jp

解法

ダイクストラやるだけ。

コード

#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <tuple>
#include <sstream>
#include <typeinfo>
#include <fstream>
#include <random>
#include <queue>
#include <deque>
#include <iterator>
#include <map>

using namespace std;
typedef long long ll;

const ll INF = 10000000000000000;

struct Edge {
  int to, color;
  ll weight;
  bool operator<(const Edge& a) const { return weight > a.weight; }
  Edge() {}
  Edge(int b, int c, ll t) { to = b, color = c, weight = t; }
};

int main() {
  int N, M;
  scanf("%d %d", &N, &M);
  vector<vector<Edge>> graph(N);
  vector<map<int, ll>> dist(N);
  vector<map<int, bool>> used(N);
  for (int i = 0; i < M; ++i) {
    int a, b, c, t;
    scanf("%d %d %d %d", &a, &b, &c, &t);
    a--;
    b--;
    Edge e1(b, c, t);
    Edge e2(a, c, t);
    dist[a][c] = INF;
    dist[b][c] = INF;
    used[a][c] = false;
    used[b][c] = false;

    graph[a].push_back(e1);
    graph[b].push_back(e2);
  }

  priority_queue<Edge> que;
  que.push(Edge(0, 1, 0));
  dist[0][1] = 0;

  ll ans = INF;
  while (!que.empty()) {
    int v = que.top().to;
    int color = que.top().color;
    ll w = que.top().weight;
    if (v == N - 1) {
      ans = w;
      break;
    }
    que.pop();
    if (used[v][color]) continue;
    used[v][color] = true;
    for (Edge e : graph[v]) {
      if (dist[e.to][e.color] > w + e.weight + abs(color - e.color)) {
        dist[e.to][e.color] = w + e.weight + abs(color - e.color);
        que.push(Edge(e.to, e.color, dist[e.to][e.color]));
      }
    }
  }
  printf("%lld\n", ans);
}