Submission #989288

#	Time	Username	Problem	Language	Result	Execution time	Memory
989288		AdamGS	Mountains (IOI17_mountains)	C++17	100 / 100	75 ms	71360 KiB

mountains

#include "mountains.h"
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=2e3+7;
pair<int,int>ma1[LIM][LIM], ma2[LIM][LIM];
ll T[LIM];
int dp[LIM][LIM], odw[LIM][LIM], n;
ll ilo(int a, int b, int c) {
  pair<ll,ll>x={b-a, T[b]-T[a]}, y={c-a, T[c]-T[a]};
  return x.st*y.nd-x.nd*y.st;
}
int solve(int l, int r) {
  if(l>r) return 0;
  if(odw[l][r]) return dp[l][r];
  odw[l][r]=1;
  if(ma1[l][r].nd!=-ma2[l][r].nd) {
    dp[l][r]=max(solve(l, -ma2[l][r].nd-1)+solve(-ma2[l][r].nd+1, r), solve(l, ma1[l][r].nd-1)+solve(ma1[l][r].nd+1, r));
    return dp[l][r];
  }
  int x=ma1[l][r].nd;
  dp[l][r]=solve(l, x-1)+solve(x+1, r);
  int sum=1, lst=x+1;
  for(int i=x+2; i<=r; ++i) {
    if(ilo(x, lst, i)>=0) {
      sum+=solve(lst+1, i-1);
      lst=i;
    }
  }
  sum+=solve(lst+1, r);
  lst=x-1;
  for(int i=x-2; i>=l; --i) {
    if(ilo(x, lst, i)<=0) {
      sum+=solve(i+1, lst-1);
      lst=i;
    }
  }
  sum+=solve(l, lst-1);
  dp[l][r]=max(dp[l][r], sum);
  return dp[l][r];
}
int maximum_deevs(vector<int>_y) {
  n=_y.size();
  rep(i, n) T[i]=_y[i];
  rep(i, n) {
    ma1[i][i]={T[i], i};
    ma2[i][i]={T[i], -i};
    for(int j=i+1; j<n; ++j) {
      ma1[i][j]=max(ma1[i][j-1], {T[j], j});
      ma2[i][j]=max(ma2[i][j-1], {T[j], -j});
    }
  }
  return solve(0, n-1);
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 30 / 30