hdu 2544 最短路

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))
{
if (n == 0 && m == 0) break;
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])
{
abc[u].push_back(v);
s[u][v] = ss;
abc[v].push_back(u);
s[v][u] = ss;
}
}
int sx, ex, b = 0;
sx = 1;

// 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;
}
}

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