poj 1502 MPI Maelstrom

poj/1502.cpp

@@ -0,0 +1,109 @@
+//poj 1502 MPI Maelstrom
+/*
+ * 第一个作为源点求spfa，输出最远距离
+ * author licatweijei
+ */
+
+#include <cstdio>
+#include <cstdlib>
+#include <iostream>
+using namespace std;
+
+#define INF 1000000
+#define MAXE 10100
+#define MAXV 10100
+#include <queue>
+#include <cstring>
+
+int dist[MAXV];
+int fa[MAXV];
+deque<int> pqu;
+bool visited[MAXV];
+int cnt[MAXV];
+
+struct edge
+{
+    int x,y,d;
+    int next;
+}edges[MAXE];
+int len;
+int first[MAXV];
+int V; // to be difine
+
+void init(int v)
+{
+    memset(cnt,0,sizeof(cnt));
+    memset(visited,false,sizeof(visited));
+    memset(first,0,sizeof(first));
+    len = 0;
+    V = v;
+
+}
+
+void add_edge(int x,int y,int d)
+{
+    ++len;
+    edges[len].x = x;
+    edges[len].y = y;
+    edges[len].d = d;
+    edges[len].next = first[x];
+    first[x] = len;
+}
+
+bool spfa(int st)
+{
+    for (int i=0;i<=V;i++)
+    {
+        dist[i] = INF;
+    }
+    dist[st] = 0;
+    visited[st] = true;
+    pqu.push_front(st);
+    while(!pqu.empty()){
+        int now = pqu.front();
+        pqu.pop_front();
+        visited[now] = false;
+        for (int nt = first[now];nt!=0;nt = edges[nt].next){
+            if (edges[nt].d + dist[now] < dist[edges[nt].y] ) {
+                dist[edges[nt].y] =  edges[nt].d + dist[now];
+                if (!visited[edges[nt].y]){
+                    visited[edges[nt].y] = true;
+                    cnt[edges[nt].y]++;
+                    if (cnt[edges[nt].y]>V) return false;
+                    if (!pqu.empty()){
+                        if (dist[edges[nt].y]>dist[pqu.front()])
+                            pqu.push_back(edges[nt].y);
+                        else
+                            pqu.push_front(edges[nt].y);
+                    } else pqu.push_front(edges[nt].y);
+                }
+            }
+        }
+    }
+    return true;
+}
+char tmp[1000];
+int main ()
+{
+    int n;
+    while(cin >> n ){
+        init(n);
+        for (int i=1;i<=n;i++){
+            for (int j=1;j<i;j++){
+
+                cin >> tmp;
+                if (tmp[0]=='x') continue;
+                int stoi = atoi(tmp) ;
+                add_edge(i,j,stoi);
+                add_edge(j,i,stoi);
+            }
+        }
+        spfa(1);
+        int ans = 0;
+        for (int i=1;i<=n;i++){
+            if (dist[i] > ans) ans = dist[i];
+        }
+
+        cout << ans << endl;
+    }
+}