Submission #366783

#TimeUsernameProblemLanguageResultExecution timeMemory
366783VEGAnn3D Histogram (COCI20_histogram)C++14
110 / 110
523 ms45676 KiB
#include <bits/stdc++.h> #define PB push_back #define sz(x) ((int)x.size()) using namespace std; typedef long long ll; const int N = 200100; const int BIG = int(4e6); const int oo = 2e9; const ll OO = 1e18; ll B[BIG], ans = 0, FRM[BIG]; int n, a[N], b[N], pref[N], suf[N], pref2[N], suf2[N]; int root[4 * N], ptr[4 * N]; int LST, K[BIG], PRV[BIG]; int NEW(int nk, ll nb, ll wh){ assert(LST < BIG); K[LST] = nk; B[LST] = nb; FRM[LST] = wh; PRV[LST] = -1; LST++; return LST - 1; } ll get_cross_point(int FI, int SE){ if (K[FI] == K[SE]) return (B[FI] > B[SE] ? -OO : OO); ll BB = B[FI] - B[SE]; ll KK = K[SE] - K[FI]; if ((BB >= 0 && KK > 0) || (BB <= 0 && KK < 0)) return BB / KK + bool(BB % KK); else return BB / KK; } void build(int v, int l, int r){ { int tit = l; while (tit < r && pref2[tit + 1] == pref2[l]) tit++; root[v] = NEW(-pref2[tit], ll(pref2[tit]) * ll(tit), -OO); ptr[v] = root[v]; for (int it = tit + 1; it <= r; it++){ int cur = NEW(-pref2[it], ll(pref2[it]) * ll(it), -OO); while (PRV[ptr[v]] > 0){ ll CR = get_cross_point(cur, ptr[v]); if (CR > FRM[ptr[v]]) break; ptr[v] = PRV[ptr[v]]; } PRV[cur] = ptr[v]; FRM[cur] = get_cross_point(cur, ptr[v]); ptr[v] = cur; } } if (l == r) return; int md = (l + r) >> 1; build(v + v, l, md); build(v + v + 1, md + 1, r); } //3166121245150 ll get_best(int v, int tl, int tr, int ql, int qr, int X){ if (ql > qr) return -OO; if (tl == ql && qr == tr){ while (FRM[ptr[v]] > X) ptr[v] = PRV[ptr[v]]; return ll(K[ptr[v]]) * ll(X) + B[ptr[v]]; } int md = (tl + tr) >> 1; return max(get_best(v + v, tl, md, ql, min(qr, md), X), get_best(v + v + 1, md + 1, tr, max(md + 1, ql), qr, X)); } void DO_IT(int l, int r){ for (int i = l; i <= r; i++) swap(a[i], b[i]); int md = (l + r) >> 1; suf[md + 1] = suf2[md + 1] = oo; for (int i = md; i >= l; i--) { suf[i] = min(suf[i + 1], a[i]); suf2[i] = min(suf2[i + 1], b[i]); } pref[md] = pref2[md] = oo; for (int i = md + 1; i <= r; i++) { pref[i] = min(pref[i - 1], a[i]); pref2[i] = min(pref2[i - 1], b[i]); } LST = 1; build(1, md + 1, r); { // min_a -- left // min_b -- right int ptr1 = md, ptr2 = md + 1; for (int i = md; i >= l; i--){ while (ptr1 < r && suf[i] <= pref[ptr1 + 1]) ptr1++; while (ptr2 <= r && suf2[i] < pref2[ptr2]) ptr2++; if (ptr1 >= ptr2) ans = max(ans, get_best(1, md + 1, r, ptr2, ptr1, i - 1) * ll(suf[i])); } } } void calc(int l, int r){ if (l == r) { ans = max(ans, ll(a[l]) * ll(b[l])); return; } DO_IT(l, r); DO_IT(l, r); int md = (l + r) >> 1; { // min_a -- left // min_b -- left int ptr1 = md, ptr2 = md; for (int i = md; i >= l; i--){ while (ptr1 < r && suf[i] <= pref[ptr1 + 1]) ptr1++; while (ptr2 < r && suf2[i] <= pref2[ptr2 + 1]) ptr2++; ll MN = min(ptr1, ptr2); if (MN > md) ans = max(ans, ll(suf[i]) * ll(suf2[i]) * (MN - ll(i) + 1ll)); } } { // min_a -- right // min_b -- right int ptr1 = md + 1, ptr2 = md + 1; for (int i = md + 1; i <= r; i++){ while (ptr1 > l && pref[i] <= suf[ptr1 - 1]) ptr1--; while (ptr2 > l && pref2[i] <= suf2[ptr2 - 1]) ptr2--; ll MX = max(ptr1, ptr2); if (MX <= md) ans = max(ans, ll(pref[i]) * ll(pref2[i]) * (ll(i) - ll(MX) + 1ll)); } } calc(l, md); calc(md + 1, r); } int main(){ ios_base::sync_with_stdio(0); cin.tie(0); #ifdef _LOCAL freopen("in.txt","r",stdin); #endif // _LOCAL cin >> n; for (int i = 1; i <= n; i++) cin >> a[i] >> b[i]; calc(1, n); cout << ans; return 0; }
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