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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long ll;
  4. #define fi first
  5. #define se second
  6. typedef pair<int, int> pii;
  7. typedef pair<pii, pii> rect;
  8.  
  9. const int MAXN = 2e5+5, LOG = 18;
  10. const int MOD = 998244353;
  11.  
  12. int n, a[MAXN], b, ans;
  13.  
  14. int main(){
  15.     cin >> n;
  16.  
  17.     for (int i =1; i <= n; i++){
  18.         cin >> a[i];
  19.         if (i ==1 && a[i] == 2) ans++;
  20.         else  if ( a[i] == 2 && b==1 && a[i-1] != 1) {
  21.             ans++; 
  22.             b =0;
  23.         }
  24.         else if ( a[i] == 2 ) b=1;
  25.  
  26.     }
  27.     cout << ans << endl;
  28. }
Success #stdin #stdout 0.01s 5284KB
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stdin
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10
1 2 2 2 1 2 1 2 2 2
stdout
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2
https://ideone.com/4ruJ68
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

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