题解 | #小红的树#

package main

import (
	"bufio"
	"fmt"
    "os"
)

var in = bufio.NewReader(os.Stdin)
var out = bufio.NewWriter(os.Stdout)

func readAlpha(b *byte) error {
	c, err := in.ReadByte()
	for ; err == nil && (c < 'A' || c > 'Z'); c, err = in.ReadByte() {
	}
	for ; err == nil && c >= 'A' && c <= 'Z'; c, err = in.ReadByte() {
		*b = c
		return nil
	}
	return err
}

func readInt(b *int) error {
    ans, read := 0, false
	c, err := in.ReadByte()
	for ; err == nil && (c < '0' || c > '9'); c, err = in.ReadByte() {
	}
	for ; err == nil && c >= '0' && c <= '9'; c, err = in.ReadByte() {
		ans = ans *10 + int(c-'0')
		read = true
	}
    if read {
        *b = ans
        return nil
    }
	return err
}
func main() {
    defer out.Flush()
	var n, q int
    readInt(&n)
    var edge = make([][]int, n+1)
    var dp = make([]int, n+1)
    var cost = make([]int, n+1)
    for i := 2; i <= n; i++ {
        var fa int
        readInt(&fa)
        edge[fa] = append(edge[fa], i)
    }
    for i:= 1; i <= n; i++ {
        var c byte
        readAlpha(&c)
        if c == 'R' {
            cost[i] =1
        }
    }
    var dfs func(int, int)
    dfs = func(root, fa int) {
        dp[root] = cost[root]
        for _, item := range edge[root] {
            if item == fa {
                continue
            }
            dfs(item, root)
            dp[root] += dp[item]
        }
    }
    dfs(1, -1)
    readInt(&q)
    for i := 0; i < q; i++ {
        var val int
        readInt(&val)
        fmt.Fprintln(out, dp[val])
    }
}