| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1161505 | RiverFlow | The Big Prize (IOI17_prize) | C++20 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
// #define LOCAL
#ifndef LOCAL
#include "prize.h"
#endif
#define nl "\n"
#define no "NO"
#define yes "YES"
#define fi first
#define se second
#define vec vector
#define task "main"
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
#define unq(x) sort(all(x)); x.resize(unique(all(x)) - x.begin())
using namespace std;
template<typename U, typename V> bool maxi(U &a, V b) {
if (a < b) { a = b; return 1; } return 0;
}
template<typename U, typename V> bool mini(U &a, V b) {
if (a > b) { a = b; return 1; } return 0;
}
const int N = (int)2e5 + 9;
const int mod = (int)1e9 + 7;
void prepare(); void main_code();
#ifdef LOCAL
int n, a[N];
array<int, 2> ask(int i) {
int x = 0, y = 0;
for(int j = i - 1; j >= 0; --j) x += a[i] > a[j];
for(int j = i + 1; j < n; ++j) y += a[i] > a[j];
return {x, y};
}
#endif
array<int, 2> d[N];
int find_best(int n) {
srand(time(NULL));
vector<int> b(n);
iota(all(b), 0);
random_shuffle(all(b));
FOR(i, 0, n - 1) d[i] = {-1, -1};
int mx = 0, luu = -1;
for(int i = 0; i < min(n, 500); ++i) {
d[ b[i] ] = ask(b[i]);
int x = d[b[i]][0] + d[b[i]][1];
if (x == 0) return b[i];
if (x > mx) {
mx = x, luu = b[i];
}
}
//chi can y ma tang len
int x=d[luu][0], y=d[luu][1];
int tx=x, ty=y;
for(int i = luu; x>0; ){
//tim vi tri tiep theo y thay doi
int lb = 0, rb=i-1, pos=-1;
while(lb<=rb){
int mid=(lb+rb)>>1;
if (d[mid][0]==-1)d[mid]=ask(mid);
int v = d[mid][0] + d[mid][1];
if (v == 0) return mid;
if (v == mx) {
if (d[mid][1] - y - (mx - (x + y)) > 0) {
rb=mid+1;
}else{
lb=mid-1;
}
}else{
pos=mid, lb=mid+1;
}
}
i=pos;
--x;
}
x=tx, y=ty;
for(int i = luu; y>0; ){
//tim vi tri tiep theo y thay doi
int lb = i+1, rb=n-1, pos=-1;
while(lb<=rb){
int mid=(lb+rb)>>1;
if (d[mid][0]==-1)d[mid]=ask(mid);
int v = d[mid][0] + d[mid][1];
if (v == 0) return mid;
if (v == mx) {
if (d[mid][0] - x - (mx - (x + y)) > 0) {
lb=mid-1;
}else{
rb=mid+1;
}
}else{
pos=mid, rb=mid-1;
}
}
i=pos;
--y;
}
return 0;
}
#ifdef LOCAL
int main() {
freopen("main.inp", "r", stdin);
cin >> n;
for(int i = 0; i < n; ++i) cin >> a[i];
int x = find_best(n);
cout << x << nl;
}
#endif
/* Let the river flows naturally */