CodeForces 86D（Yandex.Algorithm 2011 Round 2）

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include <iostream>
#define N 200010
#define LL __int64
using namespace std;
struct node {
	int l, r, id;
	int pid;
} s[N];
inline bool cmp(node a, node b) {
	return a.id < b.id || a.id == b.id && a.r < b.r;
}
int a[N];
LL ans[N];
int cnt[1000100];
LL sum = 0;
inline void add(LL x) {
	sum += x * (cnt[x] << 1 | 1);
	cnt[x]++;
}
inline void dec(LL x) {
	sum += x * (1 - (cnt[x] << 1));
	cnt[x]--;
}
int main() {
	int i, j, k, n, m, one;
	memset(cnt, 0, sizeof(cnt));
	scanf("%d%d", &n, &m);
	one = sqrt(n * 1.0);
	for (int i = 1; i <= n; ++i)
		scanf("%d", &a[i]);
	for (int i = 0; i < m; ++i) {
		scanf("%d%d", &s[i].l, &s[i].r);
		s[i].id = s[i].l / one;
		s[i].pid=i;
	}
	sort(s, s + m, cmp);
	int l, r;
	l = s[0].l;
	r = s[0].r;

	for (int i = s[0].l; i <= s[0].r; ++i)
		add(a[i]);
	ans[s[0].pid]=sum;
	for (i = 1; i < m; ++i) {
		while(r<s[i].r)add(a[++r]);
		while(r>s[i].r)dec(a[r--]);
		while(l<s[i].l)dec(a[l++]);
		while(l>s[i].l)add(a[--l]);
		ans[s[i].pid]=sum;
	}
	for(int i=0;i<m;++i)
		printf("%I64d\n",ans[i]);
	return 0;
}