# Uvalive 3486 Cells

Source: Internet
Author: User

Determine the ancestor relationship through the order of inbound and outbound Stack

Here, uvalive also

`#include <map>#include <set>#include <list>#include <cmath>#include <ctime>#include <deque>#include <stack>#include <queue>#include <cctype>#include <cstdio>#include <string>#include <vector>#include <climits>#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>#define LL long long#define PI 3.1415926535897932626using namespace std;int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}#define MAXN 20000010int pre[MAXN],post[MAXN];int start[300005],c[300005];int N;void dfs(int root){        stack<int>s;        s.push(root);        pre[root] = 0;        int dfs_clock = 0;        while (!s.empty())        {                int x = s.top();                if (pre[x])                {                        post[x] = ++dfs_clock;                        s.pop();                        continue;                }                pre[x] = ++dfs_clock;                for (int i =start[x]; i < start[x] + c[x] ; i++)                {                        if (i < N)                        {                                pre[i] = 0 ;                                s.push(i);                        }                        else                        {                                pre[i] = ++dfs_clock;                                post[i] = ++dfs_clock;                        }                }        }}int main(){        int T ,kase = 1;        scanf("%d",&T);        while (T--)        {                printf("Case %d:\n",kase++);                scanf("%d",&N);                start[0] = 1;                for (int i = 0; i < N; i++)                {                        scanf("%d",&c[i]);                        if (i)                                start[i] = start[i - 1] + c[i - 1];                }                dfs(0);                int m;                scanf("%d",&m);                while (m--)                {                        int u,v;                        scanf("%d%d",&u,&v);                        if(pre[u] < pre[v] && post[u] > post[v]) puts("Yes");                        else puts("No");                }                if (T) putchar(‘\n‘);        }}`

No, zoj is over.

Uvalive 3486 Cells

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