Company Queries II

#include<bits/stdc++.h>
//#include<unordered_set>
// #pragma GCC optimize("Ofast")
using namespace std;
#define int long long
#define die(x) return cout << x << endl, 0
#define FI first
#define SE second
#define all(o) o.begin(), o.end()
#define endl '\n'
#define IOS ios::sync_with_stdio(0), cin.tie(0)
#define FILE freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define SZ(x) ((int)(x).size())
#define PB push_back
#define PF push_front
#define POB pop_back
#define POF pop_front
#define MP make_pair
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef map<int,int> mpi;
typedef set<int> sti;
typedef vector<pii> vii;
typedef map<pii,int> mpii;
typedef set<pii> stii;
typedef long double ld;
typedef long long ll;
int gcd(int x,int y){ return (!y ? x : gcd(y, x%y)); }
int power(int x, int y) { return (!y ? 1 : power(x, y / 2) * power(x, y / 2) * (y % 2 ? x : 1)); }
int to_int(string sconvert){stringstream geek(sconvert);int xconvert = 0; geek >> xconvert; return xconvert;}
int fastMax(int x, int y) { return (((y-x)>>(32-1))&(x^y))^y; }
int fastMin(int x, int y) { return (((y-x)>>(32-1))&(x^y))^x; }
const int MAXN=2e5+30,MAX_LOG=30,MOD=1e9+7,INF=1e17;
const double PI = acos(-1);
int mod(int x) { return (x % MOD + MOD) % MOD; }


int n,m,TIMER,q;
int dp[MAX_LOG+1][MAXN];
int h[MAXN],cnt[MAXN];
vi g[MAXN];
void dfs(int d,int p){
    dp[0][d]=p;
    for(int i=1;i<=MAX_LOG;i++){
        dp[i][d]=dp[i-1][dp[i-1][d]];
    }
    for(int u:g[d]){
        if(u!=p){
            h[u]=h[d]+1;
            dfs(u,d);
            cnt[d]+=cnt[u];
        }
    }
}
int up(int v, int dist){
    for(int i=0;i<=MAX_LOG;i++){
        if(dist & (1<<i))v=dp[i][v];
    }
    return v;
}
int lca(int u,int v){
    if(u==v)return u;
    if(h[v]<h[u])swap(u,v);
    v=up(v,h[v]-h[u]);
    if(u==v)return u;
    for(int i=MAX_LOG;i>=0;i--){
        if(dp[i][u]!=dp[i][v]){
            u=dp[i][u];v=dp[i][v];
        }
    }
    if(u==v)return u;
    return dp[0][v];
}

int MAIN(){
    cin>>n>>q;
    for(int i=2;i<=n;i++){
        int p;
        cin>>p;
        g[i].PB(p);
        g[p].PB(i);
    }
    dfs(1,0);
    for(int i=0;i<q;i++){
        int u,v;
        cin>>u>>v;
        cout<<lca(u,v)<<endl;
    }
    return 0;
}

int32_t main(){
    IOS;
    int t=1;
    //cin>>t;
    while(t--)MAIN();
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED