kuangbin_ShortPath A (POJ 2387)

最短路模板题 但是其实很费时间 因为要看明白dij floyd 以及 dij优化 spfa优化 交了三次 大概是理解了

不过涉及到priority_queue的重载运算符问题 以后要在C++里面好好看看 现在不理解

Dijkstra ver:

 #include <iostream>
 #include <string>
 #include <cstdio>
 #include <cmath>
 #include <cstring>
 #include <queue>
 #include <map>
 #include <set>
 #include <vector>
 #include <algorithm>
 #define INF 0x3F3F3F3F
 using namespace std;
 typedef pair<int, int> pii;

 int size, head[], point[], next[], val[];
 int dis[], t, n;

 void add(int from, int to, int value)
 {
     point[size] = to;
     next[size] = head[from];
     val[size] = value;
     head[from] = size++;
 }

 struct cmp{
     bool operator () (pii a, pii b){
         return a.first > b.first;
     }
 };

 void dijkstra(int s)
 {
     memset(dis, 0x3F, sizeof dis);
     priority_queue<pii, vector<pii>, cmp> q;
     q.push(make_pair(, s));
     dis[s] = ;
     while(!q.empty()){
         pii u = q.top();
         q.pop();
         if(u.first > dis[u.second]) continue;
         for(int i = head[u.second]; ~i; i = next[i]){
             int j = point[i];
             if(dis[j] > u.first + val[i]){
                 dis[j] = u.first + val[i];
                 q.push(make_pair(dis[j], j));
             }
         }
     }
 }

 int main()
 {
     while(~scanf("%d%d", &t, &n)){
         size = ;
         memset(head, -, sizeof head);
         for(int i = ; i <= t; i++){
             int from, to, value;
             scanf("%d%d%d", &from, &to, &value);
             add(from, to, value);
             add(to, from, value);
         }
         dijkstra();
         printf("%d\n", dis[n]);
     }
     return ;
 }

Spfa ver:

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#define INF 0x3F3F3F3F
using namespace std;

int head[], point[], next[], val[], size;

void add(int from, int to, int value)
{
    point[size] = to;
    val[size] = value;
    next[size] = head[from];
    head[from] = size++;

    point[size] = from;
    val[size] = value;
    next[size] = head[to];
    head[to] = size++;
}

void spfa(int s, int t)
{
    int dis[];
    bool vis[];
    memset(dis, 0x3f, sizeof dis);
    memset(vis, false, sizeof vis);
    queue<int> q;
    dis[s] = ;vis[s] = true;
    q.push(s);
    while(!q.empty()){
        int u = q.front();
        q.pop();
        vis[u] = false;
        for(int i = head[u]; ~i; i = next[i]){
            int j = point[i];
            if(dis[j] > dis[u] + val[i]){
                dis[j] = dis[u] + val[i];
                if(!vis[j]){
                    q.push(j);
                    vis[j] = true;
                }
            }
        }
    }
    printf("%d\n", dis[t]);
}

int main()
{
    int t, n;
    memset(head, -, sizeof head);
    scanf("%d%d", &t, &n);
    while(t--){
        int a, b, value;
         scanf("%d%d%d", &a, &b, &value);
         add(a, b, value);
    }
    spfa(, n);
    return ;
}