关于query一点小问题
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关于query一点小问题
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Raymond_YP楼主2022/4/13 17:13
#include <iostream>
#include <cstring>

using namespace std;
#define ac cin.tie(0), cin.sync_with_stdio(0);
#define endl "\n"
typedef long long LL;

const int N = 1e5 + 10;
struct Node {
    int l, r;
    LL res;
} tr[4 * N];
int MOD;

void pushup(Node &u, Node &l, Node &r) {
    u.res = l.res * r.res % MOD;
}

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

void modify(int u, int x, int y) {
    if (tr[u].l == x && tr[u].r == x) tr[u] = {x, x, y};
    else {
        int mid = tr[u].l + tr[u].r >> 1;
        if (x <= mid) modify(u << 1, x, y);
        else modify(u << 1 | 1, x, y);
        pushup(tr[u], tr[u << 1], tr[u << 1 | 1]);
    }
}

Node query(int u, int l, int r) {
    if (tr[u].l >= l && tr[u].r <= r) return tr[u];
    else {
        int mid = tr[u].l + tr[u].r >> 1;
        if (l > mid) return query(u << 1 | 1, l, r);
        else if (r <= mid) return query(u << 1, l, r);
        else {
            Node a = query(u << 1, l, r);
            Node b = query(u << 1 | 1, l, r);
            Node res;
            pushup(res, a, b);
            return res;
        }
    }
}

int main() {
    ac
    int n;

    cin >> n;
    while (n--) {
        int m;
        cin >> m >> MOD;
        build(1, 1, m);
        for (int i = 1; i <= m; i += 1) {
            int a, b;
            cin >> a >> b;
            if (a == 1) {
                modify(1, i, b);
                cout << query(1, 1, i).res << endl;
            } else {
                modify(1, b, 1);
                cout << query(1, 1, i).res << endl;
            }
        }
    }
    return 0;
}

为什么这样写不对,改成query(1,1,m)就对了呢,把范围缩小到i,也就是当前操作的位置,应该不影响query呀?

2022/4/13 17:13
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