POJ

PKU/2485 - Highways.cpp

@@ -0,0 +1,78 @@
+#include <cstdio>
+#include <algorithm>
+
+using namespace std;
+
+struct edge{
+    int u,v,w;
+
+    edge(){}
+
+    bool operator < (edge X)const{
+        return w < X.w;
+    }
+}L[124750];
+
+int parent[500],rank[500];
+
+void init(int N){
+    for(int i = 0;i < N;++i){
+        parent[i] = i;
+        rank[i] = 0;
+    }
+}
+
+int Find(int x){
+    if(parent[x] != x) parent[x] = Find(parent[x]);
+    return parent[x];
+}
+
+void Union(int x, int y){
+    int PX = Find(x),PY = Find(y);
+
+    if(rank[PX] < rank[PY]) parent[PY] = PX;
+    else{
+        parent[PX] = PY;
+        if(rank[PX] == rank[PY]) ++rank[PY];
+    }
+}
+
+int main(){
+    int T,N,E,w;
+
+    scanf("%d",&T);
+
+    while(T--){
+        scanf("%d",&N);
+        E = 0;
+
+        for(int i = 0;i < N;++i){
+            for(int j = 0;j < N;++j){
+                scanf("%d",&w);
+
+                if(i < j){
+                    L[E].u = i;
+                    L[E].v = j;
+                    L[E].w = w;
+                    ++E;
+                }
+            }
+        }
+
+        init(N);
+        sort(L,L + E);
+
+        int ans = 0;
+
+        for(int i = 0;i < E;++i){
+            if(Find(L[i].u) != Find(L[i].v)){
+                Union(L[i].u,L[i].v);
+                ans = max(ans,L[i].w);
+            }
+        }
+
+        printf("%d\n",ans);
+    }
+
+    return 0;
+}

PKU/2593 - Max Sequence.cpp

@@ -0,0 +1,41 @@
+#include <cstdio>
+#include <algorithm>
+
+using namespace std;
+
+int main(){
+    int N,a[100000],dp1[100000],dp2[100000];
+
+    while(true){
+        scanf("%d",&N);
+        if(N == 0) break;
+
+        for(int i = 0;i < N;++i)
+            scanf("%d",&a[i]);
+
+        dp1[N-1] = a[N-1];
+
+        for(int i = N-2;i >= 0;--i)
+            dp1[i] = a[i] + max(0,dp1[i+1]);
+
+        for(int i = N-2;i >= 0;--i)
+            dp1[i] = max(dp1[i],dp1[i+1]);
+
+        dp2[0] = a[0];
+
+        for(int i = 1;i < N;++i)
+            dp2[i] = a[i] + max(0,dp2[i-1]);
+
+        for(int i = 1;i < N;++i)
+            dp2[i] = max(dp2[i],dp2[i-1]);
+
+        int ans = a[0] + a[1];
+
+        for(int i = 0;i + 1 < N;++i)
+            ans = max(ans,dp2[i] + dp1[i+1]);
+
+        printf("%d\n",ans);
+    }
+
+    return 0;
+}