【莫队】【简单的蓝题】【p2709】

题目：我谷

还是莫队啊！！！完成老贾的作业，心塞，注意一定要先扩再缩，否则会带来无法估计的后果！！！，其他地方很简单啊，详见上题莫队

#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

const int maxn = 50010, maxm = 50010;
int a[maxn], pos[maxn], c[maxn], ans;
struct query{
    int l, r, id, ans;
    bool operator < (const query &o) const { return pos[l] == pos[o.l] ? r < o.r : pos[l] < pos[o.l]; }
}q[maxm];

inline void add(int p) {
    ans -= c[a[p]] * c[a[p]]; c[a[p]]++; ans += c[a[p]] * c[a[p]];
}

inline void del(int p) {
    ans -= c[a[p]] * c[a[p]]; c[a[p]]--; ans += c[a[p]] * c[a[p]];
}

inline bool cmp1(query x, query y) {
    return x.id < y.id; 
}

int main() {
    int n, m, k;
    ans = 0;
    scanf("%d %d %d", &n, &m, &k);
    int block = (int)( n / (sqrt((double)m * 2 / 3)));
    for(int i = 1; i <= n; i++) scanf("%d", a+i);
    for(int i = 1; i <= n; i++) pos[i] = i / block;
    for(int i = 1; i <= m; i++) scanf("%d %d", &q[i].l, &q[i].r), q[i].id = i;
    sort(q+1, q+m+1);
    int l = 1, r = 0;
    for(int i = 1; i <= m; i++) {
        while(l < q[i].l) del(l++);
        while(l > q[i].l) add(--l);
        while(r < q[i].r) add(++r);
        while(r > q[i].r) del(r--);
        q[i].ans = ans;
    }
    sort(q+1, q+m+1, cmp1);
    for(int i = 1; i <= m; i++) printf("%d\n", q[i].ans);
    return 0;   
}

结束