POJ 1823 Hotel 线段树

题目链接

线段树的区间合并。

和上一题差不多....第三种操作只需要输出maxx[1]的值就可以。

#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <queue>
using namespace std;
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
const int maxn = ;
int maxx[maxn<<], pre_max[maxn<<], suf_max[maxn<<], cover[maxn<<];
void pushUp(int rt, int m) {
    maxx[rt] = max(maxx[rt<<], maxx[rt<<|]);
    pre_max[rt] = pre_max[rt<<];
    suf_max[rt] = suf_max[rt<<|];
    if(maxx[rt<<] == (m-(m>>)))
        pre_max[rt] = pre_max[rt<<] + pre_max[rt<<|];
    if(maxx[rt<<|] == (m>>))
        suf_max[rt] = suf_max[rt<<|]+suf_max[rt<<];
    maxx[rt] = max(maxx[rt], suf_max[rt<<]+pre_max[rt<<|]);
}
void build(int l, int r, int rt) {
    maxx[rt] = pre_max[rt] = suf_max[rt] = r-l+;
    cover[rt] = -;
    if(l == r)
        return ;
    int m = l+r>>;
    build(lson);
    build(rson);
}
void pushDown(int rt, int m) {
    if(~cover[rt]) {
        cover[rt<<] = cover[rt<<|] = cover[rt];
        maxx[rt<<] = pre_max[rt<<] = suf_max[rt<<] = cover[rt]*(m-(m>>));
        pre_max[rt<<|] = suf_max[rt<<|] = maxx[rt<<|] = cover[rt]*(m>>);
        cover[rt] = -;
    }
}
void update(int L, int R, int l, int r, int rt, int val) {
    if(L<=l&&R>=r) {
        cover[rt] = val;
        maxx[rt] = suf_max[rt] = pre_max[rt] = val*(r-l+);
        return ;
    }
    pushDown(rt, r-l+);
    int m = l+r>>;
    if(L<=m)
        update(L, R, lson, val);
    if(R>m)
        update(L, R, rson, val);
    pushUp(rt, r-l+);
}
int main()
{
    int n, m, sign, x, y;
    while(cin>>n>>m) {
        build(, n, );
        while(m--) {
            scanf("%d", &sign);
            if(sign == ) {
                scanf("%d%d", &x, &y);
                update(x, y+x-, , n, , );
            } else if(sign == ){
                scanf("%d%d", &x, &y);
                update(x, y+x-, , n, , );
            } else {
                printf("%d\n", maxx[]);
            }
        }
    }
}