这是我的代码：

#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;
int n, m, tot, rt[N*2], len, a[N], cnt, lsh[N * 6];

struct node {
	int v, ls, rs;
} t[N * 60];

struct ll {
	char opt;
	int A, B, C;
} qs[N*2];

int lb(int x) {
	return x & (-x);
}

void pushup(int p) {
	t[p].v = t[t[p].ls].v + t[t[p].rs].v;
}

void update(int &p, int l, int r, int k, int v) {
	if (!p) p = ++tot;
	t[p].v += v;
	if (l == r) {
		
		return;
	}
	int mid = (l + r) / 2;
	if (k <= mid) update(t[p].ls, l, mid, k, v);
	else update(t[p].rs, mid + 1, r, k, v);
}

void add(int p, int v) {
	int pos = lower_bound (lsh+1 , lsh+len+1 , a[p]) - lsh;
	for (int i = p; i <= n; i += lb(i))
		update(rt[i], 1, len, pos, v);
}

int query(int p, int l, int r, int k) {
	if (l == r) return t[p].v;
	int mid = (l + r) / 2;
	if (k <= mid) return query(t[p].ls, l, mid, k);
	else return query(t[p].rs, mid + 1, r, k);
}

int ask(int l, int r, int k) {
	int ans = 0; 
	for (int i = r; i; i -= lb(i))
		ans += query(rt[i], 1, len, k);
	for (int i = l - 1; i; i -= lb(i))
		ans -= query(rt[i], 1, len, k);
	return ans;
}

int main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	for (int i = 1; i <= m; i++) {
		char opt;
		int A, B, K;
		cin >> opt;
		cin >> A >> B;
		if (opt == 'C') {
			lsh[++cnt] = B;
			qs[i].opt = opt, qs[i].A = A, qs[i].B = B;
		} else {
			lsh[++cnt] = K;
			cin >> K;
			qs[i] = {opt, A, B, K};
		}
	}
	sort(lsh + 1, lsh + cnt + 1);
	len = unique(lsh + 1, lsh + cnt + 1) - lsh - 1;
	for (int i = 1; i <= n; i++) {
		add(i, 1);
	}
	for (int i = 1; i <= m; i++) {
		if (qs[i].opt == 'C')
			qs[i].B = lower_bound(lsh + 1, lsh + len + 1, qs[i].B) - lsh;
		else
			qs[i].C = lower_bound(lsh + 1, lsh + len + 1, qs[i].C) - lsh;
	}
	for (int i = 1; i <= m; i++) {
		if (qs[i].opt == 'C') {
			add(qs[i].A, -1);
			a[qs[i].A] = qs[i].B;
			add(qs[i].A, 1);
		} else {
			cout << ask(qs[i].A, qs[i].B, qs[i].C) << endl;
		}
	}
	return 0;
}

提交后WA 0pts
#1的错误信息是

Wrong Answer.wrong answer On line 10 column 1, read 5, expected 6.

然而经本地测试数据点1 代码输出的第十行确实是6，而非错误信息所说的5