Submission #74435

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
74435	2018-09-01 09:55:32	mjt	Mountains (IOI17_mountains)	C++11	100 / 100	21 ms	9464 KiB

mountains

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#include"mountains.h"
#include<bits/stdc++.h>
using namespace std;
const int N = 2010;
int y[N];
int f[N][N];
bool Judge(int a,int b,int c) { // a see c ?
  // ((y[a] - y[b]) / (a - b)) > ((y[a] - y[c]) / (a - c));
  return 1ll * (y[a] - y[b]) * (a - c) > 1ll * (y[a] - y[c]) * (a - b);
}
int solve(int l,int r) {
  if (f[l][r]) return f[l][r];
  if (l > r) return 0;
  if (l == r) return 1;
  int pos = -1, mx = -1;
  for (int i=l; i<=r; ++i) if (y[i] > mx) pos = i, mx = y[i];
  int ans1 = solve(l, pos - 1) + solve(pos + 1, r);
  
  int ans2 = 0;
  for (int i=pos-1,j; i>=l; i=j) {
    for (j=i-1; j>=l; --j) {
      if (Judge(j, i, pos)) {
        if (j == l) ans2 += solve(l, i - 1);
        continue;
      }
      if (j + 1 <= i - 1) ans2 += solve(j + 1, i - 1);
      break;
 
 
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• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 30 / 30