HDU 3308 LCIS

Posted 2020-12-31 devilinchina

题目大意:给予一个序列，两种操作

·查询 L-R 中的最长严格递增连续子序列的长度

·更改 LOC 的字符为X

经典的线段树区间合并，线段树种一共有三个数组

no[]当前 L到R中的最大值

ls[]从左数的最大长度

rs[]从右数的最大长度

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <map>
#include <set>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
using namespace std;
#define lowbit(x) (x&(-(x)))
typedef long long ll;
#define maxs 1000010
#define N 100005
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
int num[N];
int no[N<<2],ls[N<<2],rs[N<<2];
void pushUp(int l,int r,int rt){
    int mid = l+r>>1;
    ls[rt] = ls[rt<<1];rs[rt] = rs[rt<<1|1];
    no[rt] = max(no[rt<<1],no[rt<<1|1]);
    if(num[mid] < num[mid+1]){
        if(ls[rt] == mid-l+1)ls[rt]+=ls[rt<<1|1];
        if(rs[rt] == r-mid)rs[rt]+=rs[rt<<1];
        no[rt]  = max(no[rt],ls[rt<<1|1]+rs[rt<<1]);
    }
}
void build(int l,int r,int rt){
    if(l==r){
        no[rt] = ls[rt] = rs[rt] = 1;
        return;
    }
    int mid = l+r>>1;
    build(lson);build(rson);
    pushUp(l,r,rt);
}
void upDate(int loc,int l,int r,int rt){
    if(l==r)return;
    int mid = l+r>>1;
    if(loc<=mid)upDate(loc,lson);
    else upDate(loc,rson);
    pushUp(l,r,rt);
}
int query(int L,int R,int l,int r,int rt){
    if(L <= l and r <= R)return no[rt];
    int mid = l+r>>1;
    if(R <= mid)return query(L,R,lson);
    if(L > mid)return query(L,R,rson);
    int fi = query(L,R,lson);
    int se = query(L,R,rson);
    int ans = max(fi,se);
    if(num[mid] < num[mid+1]){
        ans = max(ans,(min(R-mid,ls[rt<<1|1])+min(mid+1-L,rs[rt<<1])));
    }
    return ans;
}
int main(){
    int T,n,m;
    char c;
    int l,r;
    cin>>T;
    while (T--){
        cin>>n>>m;
        for(int i = 1 ; i <= n ; ++i){
            scanf("%d",num+i);
        }
        build(1,n,1);
        while (m--){
            scanf(" %c",&c);
            scanf("%d%d",&l,&r);
            ++l;
            if(c==‘U‘){
                num[l] = r;
                upDate(l,1,n,1);
            }
            else{
                ++r;
                printf("%d
",query(l,r,1,n,1));
            }
        }
    }
}