POJ 3159 Candies （差分约束#1）

#include <cstdio>
#include <algorithm>
#include <queue> 
#include <cstdlib> 
#include <cstring> 
#include <stack> 
#define N 30005
#define M 150005
using namespace std; 
const int inf = (-1u >> 1); 
int n, m;
typedef pair<int, int> pii; 

int first
, d
; 
int next[M], u[M], v[M], w[M];
bool inq
;

int SPFA(int s, int n)//用栈 
{
       for (int i = 1; i <= n; i++)d[i] =  inf;
       d[s] = 0;
       stack<int> q;
       memset(inq, false, sizeof(inq)); 
       q.push(s); 
       while (!q.empty())
       {
              int x = q.top();q.pop();
              inq[x] = false;
              for (int e = first[x]; e != -1; e = next[e])if (d[v[e]] > d[u[e]] + w[e])
              {
                    d[v[e]] = d[u[e]] + w[e];
                    if (!inq[v[e]])
                    {
                              inq[v[e]] = true;
                              q.push(v[e]);
                    }
              }
       }
       return d
; 
}

void dijkstra(int s, int n)
{
        for (int i = 1;i <= n; i++)d[i] =  inf;
        d[s] = 0;
        priority_queue<pii, vector<pii>, greater<pii> > q;
        q.push(make_pair(d[s], s));
        while (!q.empty())
        {
              pii u = q.top();q.pop();
              int x = u.second;
              if (u.first != d[x])continue;
              for (int e = first[x]; e != -1; e = next[e])if (d[v[e]] > d[x] + w[e])
              {
                     d[v[e]] = d[x] + w[e];
                     q.push(make_pair(d[v[e]], v[e]));
              }
        }
} 
int main()
{
     // FILE* fp = fopen("in.txt", "r"); 
      while (scanf( "%d", &n) != EOF && n)
      {
            scanf( "%d", &m);
            int a, b, c;
            int e = 0; 
            for (int i = 1;i <= n ; i++)first[i] = -1;
            for (int i = 0; i < m; i++)
            { 
                  scanf( "%d %d %d", &a, &b, &c);
                  next[e] = first[a];
                  first[a] = e;
                  w[e] = c;
                  u[e] = a, v[e] = b;
                  e++;
            }
            dijkstra(1, n);
            printf("%d\n",  d
); 
      }
      return 0;
}