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  1.     #include <bits/stdc++.h>
  2.     // #include <ext/pb_ds/assoc_container.hpp>
  3.     // #include <ext/pb_ds/tree_policy.hpp>
  4.     using namespace std;
  5.     // using namespace __gnu_pbds;
  6.     // typedef tree<int, null_type,  less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
  7.     #define ll long long
  8.     #define ull unsigned long long
  9.     #define int long long
  10.  
  11.     int dp[5005][3] , a[505] , n;
  12.     int rec(int idx , int prev ) {
  13.         if (idx == 0 ) {
  14.             return 0 ;
  15.         }
  16.         if (idx <0)
  17.             return 1e9;
  18.         if (dp[idx][prev] != -1) return dp[idx][prev] ;
  19.         int ans= rec(idx -1 , prev)+1;
  20.         if ((a[idx]==1 || a[idx ]==3) && prev!=1) {
  21.             ans = min(ans , rec(idx - 1 , 1));
  22.         }
  23.         if ((a[idx]==2 || a[idx]==3) && prev!=2) {
  24.             ans = min(ans , rec(idx - 1 , 2));
  25.         }
  26.         return dp[idx][prev] =  ans;
  27.     }
  28.     void solve() {
  29.         cin >> n ;
  30.         for(int i = 1 ; i <= n ; i++) {
  31.             cin >> a[i] ;
  32.         }
  33.         memset(dp , -1 , sizeof(dp)) ;
  34.         cout << rec(n , 0) ;
  35.  
  36.     }
  37.  
  38.  
  39.     signed main() {
  40.     #ifndef ONLINE_JUDGE
  41.         freopen("input.txt", "r", stdin);
  42.         freopen("output.txt", "w", stdout);
  43.     #endif
  44.         ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  45.         int tc = 1;
  46.         // cin >> tc;
  47.         while (tc--) {
  48.             solve();
  49.         };
  50.         return 0;
  51.     }
Success #stdin #stdout 0.01s 5292KB
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https://ideone.com/MVVaEe
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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