SPOJ - DQUERY D-query——主席树

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区间不相同的数模板题

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e5 + 10;
int T, ks, n, m, a[maxn], pre[maxn*10], cnt, root[maxn];
struct Node { int l, r, sum; }node[maxn*40];
int p, v;
void init() {
    cnt = 0;
    memset(pre, 0, sizeof(pre));
}
void update(int l, int r, int &rootx, int rooty) {
    rootx = ++cnt; node[rootx] = node[rooty]; node[rootx].sum += v;
    if (l == r) return;
    int mid = (l + r)>>1;
    if (p <= mid) update(l, mid, node[rootx].l, node[rooty].l);
    else update(mid+1, r, node[rootx].r, node[rooty].r);
}
int query(int l, int r, int rootx) {
    if (l == r) return node[rootx].sum;
    int mid = (l + r)>>1;
    if (p <= mid) return node[node[rootx].r].sum + query(l, mid, node[rootx].l);
    else return query(mid+1, r, node[rootx].r);
}
int main() {
        scanf("%d", &n);
        for (int i = 1; i <= n; i++) {
            scanf("%d", &a[i]);
            if (!pre[a[i]]) {
                p = i, v = 1;
                update(1, n, root[i], root[i-1]);
            }
            else {
                int temp;
                p = pre[a[i]], v = -1;
                update(1, n, temp, root[i-1]);
                p = i, v = 1;
                update(1, n, root[i], temp);
            }
            pre[a[i]] = i;
        }
        scanf("%d", &m);
        while (m--) {
            int l, r; scanf("%d%d", &l, &r);
            p = l;
            printf("%d\n", query(1, n, root[r]));
        }
    return 0;
}