题解 | 小红的区间修改（一）

#include <bits/stdc++.h>
using namespace std;
class BIT {
    int n;
    std::vector<int> su;

  public:
    BIT(int n) : n(n), su(n + 1,0) {}
    void add(int x, int v) {
        for (; x <= n; x += x & (-x)) {
            su[x] += v;
        }
    }
    int query(int x) {
        int res = 0;
        for (; x; x &= x - 1) {
            res += su[x];
        }
        return res;
    }
};

int main() {
    int q;
    cin >> q;
    BIT b(300005);
    int maxLen = 0;
    while (q--) {
        int l,r;
        cin >> l >> r;
        if(b.query(r)-b.query(l-1)==0){
            b.add(l, 1);
            b.add(r,1);
            if(r-l+1>maxLen){
            maxLen = r-l+1;
        }
        }
        cout << maxLen+1 << endl;
        
    }
}