Create 3562_unfinished.cpp

SDUTOJ/3562_unfinished.cpp

@@ -0,0 +1,97 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+#define INF 0x3f3f3f3f
+
+/** SPFA 单源最短路径算法 不支持负环*/
+const int MAXN = 1005;
+int d[MAXN];/// distance [ From S to ... ]
+int v[MAXN];/// visit
+int q[MAXN];/// 基于数组的队列(也可用queue等...)
+int mp[MAXN][MAXN]; /// mp[i][j] i<--> j is connected.
+int n;/// n is the number of max Point .
+
+int path[MAXN];
+
+void spfa(int StartPoint) /// d[i] is the min distance from StartPoint to i ( Both >=1 )
+{
+    memset(d,0x3f,sizeof(int)*(n+1));
+    memset(v,0,sizeof(int)*(n+1));
+    /*
+    for(int i=1;i<MAXN;i++)
+        d[i]=INF,v[i]=0;*/
+    int cnt=0;
+    q[cnt++]=StartPoint;
+    v[StartPoint]=1;
+    d[StartPoint]=0;
+    while(cnt>0)
+    {
+        int c=q[--cnt];
+        v[c]=0;
+        for(int i=0;i<=n;i++)
+        {
+            /// Here : if your mp[i][j] use INF as infinite, then use mp[c][i]!=INF.
+            /// Or you may use mp[i][j]!=-1 && d[i] > d[c] + mp[c][i]
+            if( mp[c][i]!=INF && d[i]>d[c]+mp[c][i] )
+            {
+                d[i]=d[c]+mp[c][i];
+                //path[i]=min(path[i],path[c]);
+                if(!v[i])
+                {
+                    if(c) path[i]=path[c];
+                    v[i]=1,q[cnt++]=i;
+                }
+            }
+
+            if(c&&d[i]==d[c]+mp[c][i])
+            {
+                path[i]=min(path[i],path[c]);
+            }
+        }
+    }
+}
+
+int main()
+{
+    int t;
+    scanf("%d",&t);
+    while(t--)
+    {
+        int m;
+        scanf("%d %d",&n,&m);
+        if(!n&&!m) break;
+        n=n+1;
+
+        for(int i=0;i<=n;i++)
+        {
+            for(int j=0;j<=n;j++)
+            {
+                if(i==j) mp[i][j]=0;
+                else mp[i][j]=INF;
+            }
+        }
+        for(int i=0;i<m;i++)
+        {
+            int u,v,w;
+            scanf("%d %d %d",&u,&v,&w);
+            mp[u][v]=w;
+        }
+
+        for(int i=0; i<=n; i++)
+        {
+            if(mp[0][i]!=INF)path[i]=i;//Path Init
+        }
+
+        spfa(0);
+
+        if(d[n]<INF)
+        {
+            if(path[n]==n)printf("0\n");
+            else printf("%d\n",path[n]);
+        }
+        else printf("-1\n");
+    }
+    return 0;
+}