zoukankan      html  css  js  c++  java
  • UVa 11280 Flying to Fredericton (DP + Dijkstra)

    题意:给出n(2<=n<=100)个城市之间的m(0<=m<=1000)条航线以及对应的机票价格,要求回答一些询问,每个询问是给出最大停留次数S,求从其实城市Calgary到终点城市Fredericton中途停留次数不超过s的最便宜的路程。

    析:注意这个题是单向路,我还以为是双向的,dp[i][j] 当前在 i 城市,已经停留了 j 次, 用dijkstra 跑一次就好。

    代码如下:

    #pragma comment(linker, "/STACK:1024000000,1024000000")
    #include <cstdio>
    #include <string>
    #include <cstdlib>
    #include <cmath>
    #include <iostream>
    #include <cstring>
    #include <set>
    #include <queue>
    #include <algorithm>
    #include <vector>
    #include <map>
    #include <cctype>
    #include <cmath>
    #include <stack>
    #include <sstream>
    #include <list>
    #include <assert.h>
    #include <bitset>
    #define debug() puts("++++");
    #define gcd(a, b) __gcd(a, b)
    #define lson l,m,rt<<1
    #define rson m+1,r,rt<<1|1
    #define fi first
    #define se second
    #define pb push_back
    #define sqr(x) ((x)*(x))
    #define ms(a,b) memset(a, b, sizeof a)
    #define sz size()
    #define pu push_up
    #define pd push_down
    #define cl clear()
    #define all 1,n,1
    #define FOR(i,x,n)  for(int i = (x); i < (n); ++i)
    #define freopenr freopen("in.txt", "r", stdin)
    #define freopenw freopen("out.txt", "w", stdout)
    using namespace std;
    
    typedef long long LL;
    typedef unsigned long long ULL;
    typedef pair<int, int> P;
    const int INF = 0x3f3f3f3f;
    const double inf = 1e20;
    const double PI = acos(-1.0);
    const double eps = 1e-8;
    const int maxn = 100 + 10;
    const int maxm = 1e5 + 10;
    const int mod = 50007;
    const int dr[] = {-1, 0, 1, 0};
    const int dc[] = {0, -1, 0, 1};
    const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};
    int n, m;
    const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    inline bool is_in(int r, int c) {
      return r >= 0 && r < n && c >= 0 && c < m;
    }
    
    map<string, int> mp;
    
    int ID(const string &s){
      if(mp.count(s))  return mp[s];
      return mp[s] = mp.sz;
    }
    
    struct Edge{
      int to, val, next;
    };
    Edge edges[maxn*10<<1];
    int head[maxn], cnt;
    
    void addEdge(int u, int v, int c){
      edges[cnt].to = v;
      edges[cnt].val = c;
      edges[cnt].next = head[u];
      head[u] = cnt++;
    }
    
    int dp[maxn][maxn];
    bool vis[maxn];
    
    int main(){
      ios::sync_with_stdio(false);
      int T;   cin >> T;
      for(int kase = 1; kase <= T; ++kase){
        cin >> n;
        int s, t;
        mp.cl;
        for(int i = 0; i < n; ++i){
          string ss;
          cin >> ss;
          if(ss == "Calgary")  s = ID(ss);
          else if(ss == "Fredericton")  t = ID(ss);
          else ID(ss);
        }
        ms(head, -1);  cnt = 0;
        cin >> m;
        while(m--){
          string ss, tt;
          int d;
          cin >> ss >> tt >> d;
          int u = ID(ss), v = ID(tt);
          if(u == v)  continue;
          addEdge(u, v, d);
        }
        ms(dp, INF);  ms(vis, 0);
        dp[s][0] = 0;  vis[s] = 1;
        queue<P> q;  q.push(P(s, 0));
        while(!q.empty()){
          P p = q.front();  q.pop();
          int u = p.fi, j = p.se;
          for(int i = head[u]; ~i; i = edges[i].next){
            int v = edges[i].to;
            if(dp[v][j+1] > dp[u][j] + edges[i].val){
              dp[v][j+1] = dp[u][j] + edges[i].val;
              q.push(P(v, j+1));
            }
          }
        }
        if(kase > 1)  cout << endl;
        cout << "Scenario #" << kase << endl;
        cin >> m;
        while(m--){
          int x;  cin >> x;  ++x;
          int ans = INF;
          for(int i = 0; i <= x; ++i)  ans = min(ans, dp[t][i]);
          if(ans == INF)  cout << "No satisfactory flights
    ";
          else  cout << "Total cost of flight(s) is $" << ans << endl;
        }
      }
      return 0;
    }
    

      

  • 相关阅读:
    c#中的as,is和强转
    Shader中的lerp
    [RequireComponent(typeof(....))]
    [ExecuteInEditMode]
    在ugui上显示3d物体
    T4语法快速入门
    MVC生命周期
    MVC5路由系统机制详细讲解
    FluentScheduler定时器计划任务
    MVC的WebViewPage
  • 原文地址:https://www.cnblogs.com/dwtfukgv/p/7743425.html
Copyright © 2011-2022 走看看