Hihocoder 1224: Racing

Links: http://hihocoder.com/problemset/problem/1224

Deep Search to find the maximum depth, from the maximum depth of the leaves back to the root of each vertex through the deep search for maximum depth

#include <iostream> #include <math.h> #include <stdio.h> #include <queue> #include <string.h > #include <algorithm>using namespace std;const int maxn=100000+10;struct node{int v,next;} edge[maxn];struct node{int start,step;} P[maxn];int head[maxn],vis[maxn],length[maxn],pre[maxn],temp,ldeepv;void Add (int u,int V,int index) {Edge[index].v=v    ;    Edge[index].next=head[u]; Head[u]=index;}        void dfs (int v,int length)//seek maximum depth {if (temp<length) {temp=length;    Ldeepv=v;    } if (Vis[v]) return;    Vis[v]=1;    for (int i=head[v];i!=-1;i=edge[i].next) {if (!VIS[EDGE[I].V]) DFS (edge[i].v,length+1);    }}int Main () {int n;        while (~SCANF ("%d", &n)) {int a,b,cnt=0;        memset (head,-1,sizeof (head));        memset (length,0,sizeof (length));        memset (pre,0,sizeof (pre));            for (int i=1;i<n;i++) {scanf ("%d%d", &a,&b);            Add (a,b,i); Pre[b]=a;       } ldeepv=temp=0;        DFS (1,0);  Length[cnt++]=temp;        Deposit Length//printf ("%d\n", temp);        int K=LDEEPV;        memset (vis,0,sizeof (VIS));            while (pre[k]!=0)//backtracking {vis[k]=1;            K=PRE[K];            Temp=0;            DFS (k,0);        Length[cnt++]=temp;        } sort (length,length+cnt);    printf ("%d\n", Length[cnt-1]+length[cnt-2]); } return 0;}

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Hihocoder 1224: Racing