Create 1874.cpp

HDOJ/1874.cpp

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+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+
+#define INF 0x3f3f3f3f
+
+namespace SPFA
+{
+const int MAXN = 256;
+int d[MAXN];/// distance [ From S to ... ]
+int v[MAXN];/// visit
+int q[MAXN];///
+int mp[MAXN][MAXN]; /// mp[i][j] i<--> j is connected.
+int n;
+
+int spfa(int s,int t)
+{
+    memset(d,0x3f,sizeof(d));
+    memset(v,0,sizeof(v));
+    /*
+    for(int i=1;i<MAXN;i++)
+        d[i]=INF,v[i]=0;*/
+    int cnt=0;
+    q[cnt++]=s;
+    v[s]=1;
+    d[s]=0;
+    while(cnt>0)
+    {
+        int c=q[--cnt];
+        v[c]=0;
+        for(int i=1;i<=n;i++)
+        {
+            if(mp[c][i]!=INF&&d[i]>d[c]+mp[c][i])
+            {
+                d[i]=d[c]+mp[c][i];
+                if(!v[i])   v[i]=1,q[cnt++]=i;
+            }
+        }
+    }
+    return d[t];
+}
+
+}/// End of NameSpace SPFA
+
+int main()
+{
+    using namespace SPFA;
+    int N,M;
+    while(scanf("%d %d",&N,&M)==2)
+    {
+        memset(mp,0x3f,sizeof(mp));
+        for(int i=0;i<M;i++)
+        {
+            int a,b,cost;
+            scanf("%d %d %d",&a,&b,&cost);
+            ++a;++b;
+            if(mp[a][b]>cost)
+            {
+                mp[b][a]=mp[a][b]=cost;
+            }
+        }
+        int s,t;
+        scanf("%d %d",&s,&t);
+        if(s==t)
+        {
+            printf("0\n");continue;
+        }
+        ++s;++t;
+        SPFA::n=N;
+        int ans=spfa(s,t);
+        printf("%d\n",ans>=INF ? -1 : ans );
+    }
+    return 0;
+}