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| #include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#define maxn 100010
#define ll long long
using namespace std;
int n, m, k, a[maxn];
int b[maxn];
void init_hash() {
for (int i = 1; i <= n; ++i) b[i] = a[i];
sort(b + 1, b + n + 1); int cnt = unique(b + 1, b + n + 1) - b - 1;
for (int i = 1; i <= n; ++i) a[i] = lower_bound(b + 1, b + cnt + 1, a[i]) - b;
}
int blo, bl[maxn], R[maxn];
struct Query {
int l, r, k, id;
friend bool operator < (const Query &u, const Query &v) {
if (bl[u.l] == bl[v.l]) return u.r < v.r;
return u.l < v.l;
}
} Q[maxn];
ll s1[maxn], s2[maxn], Ans[maxn], ans;
inline void add(int v, ll &ans) {
s1[v] += b[v];
ans = max(ans, s1[v]);
}
inline void Add(int v, ll &ans) {
s2[v] += b[v];
ans = max(ans, s1[v] + s2[v]);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n >> m; blo = sqrt(n);
for (int i = 1; i <= n; ++i) cin >> a[i]; init_hash();
for (int i = 1; i <= m; ++i) cin >> Q[i].l >> Q[i].r, Q[i].id = i;
for (int i = 1; i <= n; ++i) bl[i] = (i - 1) / blo + 1, R[bl[i]] = bl[i] * blo;
sort(Q + 1, Q + m + 1);
for (int o = 1, p = 1; o <= m; o = p) {
while (bl[Q[o].l] == bl[Q[p].l]) ++p;
ll ans = 0; int r = R[bl[Q[o].l]], _r = r; fill(s1, s1 + maxn, 0);
for (int i = o; i < p; ++i) {
while (r < Q[i].r) add(a[++r], ans);
Ans[Q[i].id] = ans;
for (int j = Q[i].l; j <= min(Q[i].r, _r); ++j) Add(a[j], Ans[Q[i].id]);
for (int j = Q[i].l; j <= min(Q[i].r, _r); ++j) s2[a[j]] = 0;
}
}
for (int i = 1; i <= m; ++i) cout << Ans[i] << "\n";
return 0;
}
|