hdu 1874 畅通工程续

SPFA

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn = 2222;
vector<int>abc[maxn];
int s[maxn][maxn];
int js[maxn];
struct aaa{
    int s, node;
}dt[maxn];
bool cmp(const aaa&a, const aaa&b)
{
    return a.s<b.s;
}
int main()
{
    int n, m;
    while (~scanf("%d%d", &n, &m))
    {
        int i, u, v, ss, j;
        for (i = 0; i <= n; i++) for (j = 0; j <= n; j++) s[i][j] = 999999999;
        for (i = 0; i<maxn; i++) js[i] = 999999999;
        for (i = 0; i<maxn; i++) abc[i].clear();
        for (i = 1; i <= m; i++)
        {
            scanf("%d%d%d", &u, &v, &ss);
            if (ss<s[u][v])//选择最短的一条边
            {
                abc[u].push_back(v);
                s[u][v] = ss;
                abc[v].push_back(u);
                s[v][u] = ss;
            }
        }
        int sx, ex, b = 0;
        scanf("%d%d", &sx, &ex);
        js[sx] = 0;//第一个点
        dt[0].node = sx;
        dt[0].s = 0;
        for (i = 0; i <= b; i++)
        {
          //  sort(dt + i, dt + b, cmp);
            for (j = 0; j<abc[dt[i].node].size(); j++)
            {

                int yy = s[dt[i].node][abc[dt[i].node][j]];
                if (yy != 0)
                {
                    if (dt[i].s + yy<js[abc[dt[i].node][j]])
                    {
                        b++;
                        dt[b].node = abc[dt[i].node][j];
                        dt[b].s = dt[i].s + yy;
                        js[abc[dt[i].node][j]] = dt[i].s + yy;
                    }
                }

            }
        }
        if (js[ex] == 999999999)  printf("%d
", -1);
        else printf("%d
", js[ex]);
    }
    return 0;
}