Submission #1358342

#TimeUsernameProblemLanguageResultExecution timeMemory
1358342JohanAlternating Heights (CCO22_day1problem1)C++20
10 / 25
1095 ms4464 KiB
#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int a[N], ans[N];
bool is_cycle = false;
vector < int > color, adj[N];
void dfs(int u){
  if(is_cycle)return;
  color[u] = 1;
  for(auto v : adj[u]){
    if(color[v] == -1)
      dfs(v);
    else if(color[v] == 1){
      is_cycle = true;
      return;
    }
  }
  color[u] = 2;
}
bool ask(int l, int r){
  if(l == r)
    return false;
  set < int > dif;
  for(int i = l; i <= r; i++)
    dif.insert(a[i]);
  for(int i = l; i < r; i++){
    if((i - l + 1) % 2 == 0){
      adj[a[i]].push_back(a[i + 1]);
    }
    else{
      adj[a[i + 1]].push_back(a[i]);
    }
  }
  is_cycle = false;
  for(auto i : dif){
    if(color[i] == -1)
      dfs(i);
  }  for(auto i : dif){
    adj[i].clear();
    color[i] = -1;
  }
  return is_cycle;
}
signed main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, k, q;
  cin >> n >> k >> q;
  for(int i = 1; i <= n; i++)
    cin >> a[i];
  color.assign(k + 1, -1);
  for(int i = 1; i <= n; i++){
    int l = i, r = n;
    int best = n + 1;
    while(r >= l){
      int mid = (l + r) >> 1;
      if(ask(i, mid) == true){
        best = mid;
        r = mid - 1;
      }
      else l = mid + 1;
    }
    ans[i] = best;
  }
  while(q--){
    int l, r;
    cin >> l >> r;
    if(ans[l] > r){
      cout << "YES\n";
    }
    else {
      cout << "NO\n";
    }
  }
}
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