卿学姐与公主 UESTC - 1324 分块模板题

Posted 2020-10-26 COLORFUL

题意：http://acm.uestc.edu.cn/#/problem/show/1324 中文题，自己看喽。

题解：分块模板，update时顺便更新块属性。ask时先判掉belong[l]==belong[r]。build函数时直接用模板喽。

坑：打错了个字母，改了一下还改错了。还写错个括号。

ac代码：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<queue>
#include<string.h>
#include<iostream>
#include<cmath>
using namespace std;
const long long maxn = 100005;
int belong[maxn], num, block, l[maxn], r[maxn],  n, q;
long long Max[maxn], a[maxn];
void build() 
{
    block = sqrt(n);
    num = n / block;
    if (n%block) num++;
    for (int i = 1; i <= num; i++) 
        l[i] = (i - 1) * block + 1, r[i] = i*block;
    r[num] = n;
    for (int i = 1; i <= n; i++) {
        belong[i] = (i - 1) / block + 1;
    }
        
    for (int i = 1; i <= num; i++) 
        for (int j = l[i]; j <= r[i]; j++)
            Max[i] = max(Max[i], a[j]);
    
}
void update(int x, int y) {
    a[x] += y;
    Max[belong[x]] = max(Max[belong[x]], a[x]);
}
long long ask(int x, int y) {
    long long ans = 0;
    if (belong[x] == belong[y]) {
        for (int i = x; i <= y; i++) ans = max(ans, a[i]);
        return ans;
    }
    for (int i = x; i <= r[belong[x]]; i++) {
        ans = max(ans, a[i]);
    }
    for (int i = belong[x] + 1; i < belong[y]; i++) {
        ans = max(ans, Max[i]);
    }
    for (int i = l[belong[y]]; i <= y; i++) {
        ans = max(ans, a[i]);
    }
    return ans;
}
int main() {
    scanf("%d%d", &n, &q);
    build();

    for (int i = 1; i <= q; i++) {
        int op, l, r;
        scanf("%d%d%d", &op, &l, &r);
        if (op == 1)update(l, r);
        else printf("%lld\\n", ask(l, r));

    }
}

 看到了2014年6月的卿学姐刷题推荐http://www.cnblogs.com/qscqesze/p/3852521.html 1320道题吧。。。Orz