【Vjudge】P1989Subpalindromes（线段树）

　　题目链接

　　水题一道，用线段树维护哈希值，脑补一下加减乱搞搞……注意细节就过了

　　一定注意细节……

#include<cstdio>
#include<cstdlib>
#include<cctype>
#include<algorithm>
#include<cstring>
#define maxn 100050
#define base 163
#define left (rt<<1)
#define right (rt<<1|1)
#define mid ((l+r)>>1)
#define lson l,mid,left
#define rson mid+1,r,right
using namespace std;

unsigned long long d[maxn*5];
unsigned long long w[maxn*5];
unsigned long long bs[maxn];
char q[maxn];

inline int count(char c){    return c-'a'+1;    }

inline void pushup(int rt,int m){
    d[rt]=d[left]*bs[m>>1]+d[right];
    w[rt]=w[right]*bs[m-(m>>1)]+w[left];
}

void build(int l,int r,int rt){
    if(l==r){
        d[rt]=w[rt]=count(q[l]);
        return;
    }
    build(lson);
    build(rson);
    pushup(rt,r-l+1);
}

unsigned long long queryfro(int from,int to,int l,int r,int rt){
    if(from<=l&&to>=r)    return d[rt];
    unsigned long long ans=0;
    int len=0;
    if(to>mid){
        len=min(to,r)-mid;
        ans=queryfro(from,to,rson);
    }
    if(from<=mid)    ans+=queryfro(from,to,lson)*bs[len];
    return ans;
}

unsigned long long querysub(int from,int to,int l,int r,int rt){
    if(from<=l&&to>=r)    return w[rt];
    unsigned long long ans=0;
    int len=0;
    if(from<=mid){
        len=mid-max(from,l)+1;
        ans=querysub(from,to,lson);
    }
    if(to>mid)    ans+=querysub(from,to,rson)*bs[len];
    return ans;
}

void update(int o,char c,int l,int r,int rt){
    if(l==r){
        d[rt]=w[rt]=count(c);
        return;
    }
    if(o<=mid)    update(o,c,lson);
    else        update(o,c,rson);
    pushup(rt,r-l+1);
}

int main(){
    scanf("%s",q+1);
    int n=strlen(q+1),m;
    scanf("%d",&m);
    bs[0]=1;        for(int i=1;i<=n;++i)    bs[i]=bs[i-1]*base;
    build(1,n,1);
    for(int i=1;i<=m;++i){
        char c[15];    int x,y;char o[10];
        scanf("%s%d",c,&x);
        if(c[0]=='p'){
            scanf("%d",&y);
            if(queryfro(x,y,1,n,1)==querysub(x,y,1,n,1))    printf("Yes
");
            else    printf("No
");
        }
        else{
            scanf("%s",o);
            update(x,o[0],1,n,1);
        }
    }
    return 0;
}
/*
abcda
5
palindrome? 1 5
palindrome? 1 1
change 4 b
palindrome? 1 5
palindrome? 2 4
*/