AcWing算法提高课【第四章高级数据结构】线段树

最大数

链接：https://www.acwing.com/problem/content/1277/

 

代码：

#include <bits/stdc++.h>

using namespace std;

const int N = 200010;

struct Node 
{
    int l, r, mx;
}tr[N * 4];

int m, p;

void build(int u, int l, int r)
{
    tr[u] = {l, r};
    if (l == r) return;
    int mid = (l + r) >> 1;
    build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
}

void change(int u, int x, int v)
{
    if (tr[u].l == x && tr[u].r == x) 
    {
        tr[u] = {x, x, v};
        return;
    }
    
    int mid = (tr[u].l + tr[u].r) >> 1;
    if (x <= mid) change(u << 1, x, v);
    if (x > mid) change(u << 1 | 1, x, v);
    tr[u].mx = max(tr[u << 1].mx, tr[u << 1 | 1].mx);
}

int query(int u, int l, int r)
{
    if (l <= tr[u].l && tr[u].r <= r) 
    {
        return tr[u].mx;
    }
    
    int mid = (tr[u].l + tr[u].r) >> 1;
    int v = 0;
    if (l <= mid) v = query(u << 1, l, r);
    if (r > mid) v = max(v, query(u << 1 | 1, l, r));
    return v;
}
int main()
{
    cin >> m >> p;
    
    build(1, 1, m);
    
    int last = 0, n = 0;
    while (m -- ) 
    {
        char op[2];
        int x; 
        cin >> op >> x;
        if (*op == 'Q')
        {
            last = query(1, n - x + 1, n);
            cout << last << "\n";
        }
        else 
        {
            change(1, n + 1, (x + last) % p);
            n ++;
        }
    }
    
    return 0;
}