File size: 2,551 Bytes
c4b0eef |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 |
// #pragma GCC optimize("Ofast,unroll-loops")
// #pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define dd double
#define ld long double
#define sl(n) scanf("%lld", &n)
#define si(n) scanf("%d", &n)
#define sd(n) scanf("%lf", &n)
#define pll pair <ll, ll>
#define pii pair <int, int>
#define mp make_pair
#define pb push_back
#define all(v) v.begin(), v.end()
#define inf (1LL << 62)
#define loop(i, start, stop, inc) for(ll i = start; i <= stop; i += inc)
#define for1(i, stop) for(ll i = 1; i <= stop; ++i)
#define for0(i, stop) for(ll i = 0; i < stop; ++i)
#define rep1(i, start) for(ll i = start; i >= 1; --i)
#define rep0(i, start) for(ll i = (start-1); i >= 0; --i)
#define ms(n, i) memset(n, i, sizeof(n))
#define casep(n) printf("Case %lld:", ++n)
#define pn printf("\n")
#define pf printf
#define EL '\n'
#define fastio std::ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
const ll sz = 5e4 + 10;
pii ara[sz], lst[sz];
ll pnt[sz], dp[sz];
struct Line {
ll m, c;
} tree[4*sz];
bool exist[4*sz];
inline ll f(Line &line, ll x) {
return line.m*x + line.c;
}
void add(ll lo, ll hi, Line line, ll node)
{
exist[node] = 1;
if(lo == hi) {
if(f(line, pnt[lo]) < f(tree[node], pnt[lo]))
tree[node] = line;
return;
}
ll mid = lo+hi >> 1;
bool l = f(line, pnt[lo]) < f(tree[node], pnt[lo]);
bool m = f(line, pnt[mid]) < f(tree[node], pnt[mid]);
if(m) swap(tree[node], line);
if(l != m) add(lo, mid, line, node<<1);
else add(mid +1, hi, line, node<<1|1);
}
ll query(ll lo, ll hi, ll idx, ll node)
{
if(lo == hi)
return f(tree[node], pnt[idx]);
ll mid = lo+hi >> 1, ret = f(tree[node], pnt[idx]);
if(idx <= mid && exist[node<<1]) ret = min(ret, query(lo, mid, idx, node<<1));
else if(idx > mid && exist[node<<1|1]) ret = min(ret, query(mid+1, hi, idx, node<<1|1));
return ret;
}
int main()
{
ll n;
cin >> n;
for1(i, n) {
si(ara[i].first), si(ara[i].second);
}
sort(ara+1, ara+n+1);
ll mxw = 0, idx = 0;
rep1(i, n) {
if(ara[i].second > mxw)
lst[++idx] = ara[i];
mxw = max(mxw, (ll)ara[i].second);
}
reverse(lst+1, lst+idx+1);
for1(i, idx) pnt[i] = lst[i].first;
for0(i, 4*sz) tree[i] = {0, inf};
for1(i, idx) {
add(1, idx, {lst[i].second, dp[i-1]}, 1);
dp[i] = query(1, idx, i, 1);
}
cout << dp[idx] << EL;
return 0;
|