CF570D Tree Requests

#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;

const int N = 5e5 + 5;
const int M = 30;

int n, qn, tot = 0, head[N];
int dfsc = 0, dep[N], id[N], siz[N];
char let[N];
vector <int> vec[N];

struct Edge {
    int to, nxt;
} e[N << 1];

inline void add(int from, int to) {
    e[++tot].to = to;
    e[tot].nxt = head[from];
    head[from] = tot;
}

struct Querys {
    int x, h, res, id;
    
    friend bool operator < (const Querys &u, const Querys &v) {
        return u.h < v.h;
    }
    
} q[N];

inline void read(int &X) {
    X = 0; char ch = 0; int op = 1;
    for(; ch > ‘9‘|| ch < ‘0‘; ch = getchar())
        if(ch == ‘-‘) op = -1;
    for(; ch >= ‘0‘ && ch <= ‘9‘; ch = getchar())
        X = (X << 3) + (X << 1) + ch - 48;
    X *= op;
}

bool cmp(int x, int y) {
    return dep[x] < dep[y];
}

inline void chkMax(int &x, int y) {
    if(y > x) x = y;
}

void dfs(int x, int fat, int depth) {
    dep[x] = depth, id[x] = ++dfsc, siz[x] = 1;
    for(int i = head[x]; i; i = e[i].nxt) {
        int y = e[i].to;
        if(y == fat) continue;
        dfs(y, x, depth + 1);
        siz[x] += siz[y];
    }
}

namespace Bit {
    int s[M][N];
    
    #define lowbit(p) (p & (-p))
    
    inline void modify(int t, int p, int v) {
        for(; p <= n; p += lowbit(p))
            s[t][p] += v;
    }
    
    inline int query(int t, int p) {
        int res = 0;
        for(; p > 0; p -= lowbit(p))
            res += s[t][p];
        return res;
    }
    
} using namespace Bit;

int main() {
//    freopen("Sample.txt", "r", stdin);
//    freopen("my.out", "w", stdout);
    
    read(n), read(qn);
    for(int fat, i = 2; i <= n; i++) {
        read(fat);
        add(fat, i), add(i, fat);
    }
    dfs(1, 0, 1);
    
    int maxd = 0;
    for(int i = 1; i <= n; i++) {
        chkMax(maxd, dep[i]);
        vec[dep[i]].push_back(i);
    }
    
    scanf("%s", let + 1);
    for(int i = 1; i <= qn; i++) {
        q[i].res = 0, q[i].id = i;
        read(q[i].x), read(q[i].h);
    }
            
    sort(q + 1, q + 1 + qn);
    for(int i = 1; i <= qn; i++) {
        int lst = i;
        for(; q[i].h == q[lst].h; i++);
        i--;
        if(q[i].h > maxd) continue;
        
        int vecSiz = vec[q[i].h].size();
        for(int j = 0; j < vecSiz; j++) {
            int pos = vec[q[i].h][j];
            modify(let[pos] - ‘a‘, id[pos], 1);
        }
        
        for(int j = lst; j <= i; j++) 
            for(int c = 0; c < 26; c++) {
                int tmp = query(c, id[q[j].x] + siz[q[j].x] - 1) - query(c, id[q[j].x] - 1);
                if(tmp & 1) ++q[q[j].id].res;
            }
        
        for(int j = 0; j < vecSiz; j++) {
            int pos = vec[q[i].h][j];
            modify(let[pos] - ‘a‘, id[pos], -1);
        }
    }
    
/*    for(int i = 1; i <= qn; i++)
        printf("%d ", q[i].res);
    printf("\n");   */
    
    for(int i = 1; i <= qn; i++)
        if(q[i].res <= 1) puts("Yes");
        else puts("No");
    
    return 0;
}