SPOJ DQUERY - D-query （树状数组求区间种类数）

https://www.spoj.com/problems/DQUERY/
求区间种类数

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 1000000;
const int MAXM = 30010;
struct Q{
    int l, r, id;
}ask[MAXN];
int c[MAXN + 10], a[MAXM], last[MAXN + 10];
void add(int p, int val){
    for(int i = p; i <= MAXN; i += i & (-i))
        c[i] += val;
}
int sum(int p){
    int ans = 0;
    for(int i = p; i >= 1; i -= i & (-i))
        ans += c[i];
    return ans;
}
int ans[MAXN];
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, q;
    cin >> n;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    cin >> q;
    for(int i = 0; i < q; ++i)
        cin >> ask[i].l >> ask[i].r, ask[i].id = i;
    sort(ask, ask + q, [](Q &x, Q &y)->bool{return x.r < y.r;});
    int now = 0;
    for(int i = 1; i <= n; ++i){
        if(last[a[i]]) add(last[a[i]], -1);
        add(i, 1);
        last[a[i]] = i;
        while(ask[now].r == i){
            ans[ask[now].id] = sum(i) - sum(ask[now].l - 1);
            ++now;
        }
    }
    for(int i = 0; i < q; ++i) cout << ans[i] << '\n';
    return 0;
}

标签：int,cin,DQUERY,SPOJ,MAXN,ans,ask,query,id
来源： https://www.cnblogs.com/Zeronera/p/14471757.html