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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. namespace std {
  6. #ifndef LOCAL
  7. #define cerr \
  8.   if (0) cerr
  9. #endif
  10. }  // namespace std
  11.  
  12. int a[200005];
  13. int dp[200005][2];
  14. int n, q;
  15.  
  16. int32_t main() {
  17.   ios_base::sync_with_stdio(0);
  18.   cin.tie(0);
  19. #ifdef LOCAL
  20. #define task "a"
  21. #else
  22. #define task "CLIMBING"
  23. #endif
  24.   if (fopen(task ".inp", "r")) {
  25.     freopen(task ".inp", "r", stdin);
  26.     freopen(task ".out", "w", stdout);
  27.   }
  28.   cin >> n >> q;
  29.   for (int i = 1; i <= n; i++) {
  30.     cin >> a[i];
  31.   }
  32.   while (q--) {
  33.     int l, r;
  34.     cin >> l >> r;
  35.     // dp[i, last_sign]
  36.     // sign = 0: <
  37.     // sign = 1: >
  38.     int ret = 0;
  39.     for (int i = l; i <= r; i++) {
  40.       dp[i][1] = 1;
  41.       dp[i][0] = -1e9;
  42.       for (int j = l; j < i; j++) {
  43.         if (a[j] < a[i]) {
  44.           dp[i][0] = max(dp[i][0], dp[j][1] + 1);
  45.         }
  46.         if (a[j] > a[i]) {
  47.           dp[i][1] = max(dp[i][1], dp[j][0] + 1);
  48.         }
  49.       }
  50.       ret = max(ret, dp[i][1]);
  51.     }
  52.     cout << ret << "\n";
  53.   }
  54.   return 0;
  55. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/aRr3lW
language:
C++14 (gcc 8.3)
created:
9 hours ago
visibility:
public

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