题目大意

静态区间查询不同数的个数。

分析

好了，成功被这道题目拉低了AC率。。。
打了莫队T飞掉了，真的是飞掉了QwQ。
蒟蒻想不出主席树的做法，就换成了莫队。。。

#include <bits/stdc++.h>
#define ll long long
#define ms(a, b) memset(a, b, sizeof(a))
#define inf 0x3f3f3f3f
#define N 500005
#define M 1000005
using namespace std;
template <typename T>
inline void read(T &x) {
    x = 0; T fl = 1; char ch = 0;
    for (; ch < '0' || ch > '9'; ch = getchar())
        if (ch == '-') fl = -1;
    for (; ch >= '0' && ch <= '9'; ch = getchar())
        x = (x << 1) + (x << 3) + (ch ^ 48);
    x *= fl;
}
int buf[1 << 20];
template <typename T>
inline void write(T x) {
    if (x < 0) putchar('-'), x = -x;
    if (x > 9) write(x / 10);
    putchar(x % 10 + '0');
}
struct node {
    int l, r, bl, id;
    bool operator <(const node &rhs) const {
        return (bl == rhs.bl)? ((bl & 1)? (r < rhs.r): (r > rhs.r)): (bl < rhs.bl);
    }
}q[N];
int block, res = 0, n, m;
int clo[M], a[N], ans[N];
inline void update(register int x, register int opt) {
    clo[a[x]] += opt;
    if (opt == -1) if (clo[a[x]] == 0) res += opt;
    if (opt == 1) if (clo[a[x]] == 1) res += opt;
}
int main() {
    read(n); block = sqrt(n);
    for (register int i = 1; i <= n; ++ i) read(a[i]);
    read(m);
    for (register int i = 1; i <= m; ++ i) {
        read(q[i].l); read(q[i].r);
        q[i].bl = (q[i].l + 1) / block;
        q[i].id = i;
    }
    sort(q + 1, q + 1 + m);
    register int l = 1, r = 0;
    for (register int i = 1; i <= m; ++ i) {
        while (r < q[i].r) update(++ r, 1);
        while (r > q[i].r) update(r --, -1);
        while (l > q[i].l) update(-- l, 1);
        while (l < q[i].l) update(l ++, -1);
        ans[q[i].id] = res;
    }
    for (register int i = 1; i <= m; ++ i) write(ans[i]), putchar('\n');
    return 0;
}

原文地址：https://www.cnblogs.com/chhokmah/p/10629018.html