2023 rcpc

2023/rcpc/d1/editorial/E. Anton Would Approve This Problem - dp.cpp

@@ -0,0 +1,46 @@
+/// Banu Denis - dp
+#include <bits/stdc++.h>
+
+using namespace std;
+#define ll long long
+#define ld long double
+#define ull unsigned long long
+#define pii pair<int,int>
+#define MOD 1000000007
+#define zeros(x) x&(x-1)^x
+#define fi first
+#define se second
+#define NMAX 500005
+const long double PI = acos(-1);
+
+int n,t, dp[2][4];
+string s;
+
+int main(){
+  ios::sync_with_stdio(false);
+  cin >> t;
+  while (t--) {
+    cin >> n;
+    cin >> s;
+    memset(dp,0,sizeof(dp));
+    int crt = 1;
+    for (int i=0;i<s.size();i++) {
+      crt = (crt^1);
+      if (s[i] == '0') {
+        dp[crt][0] = max(dp[crt^1][0] + 1, dp[crt^1][2] + 1);
+        dp[crt][1] = dp[crt^1][1];
+        dp[crt][2] = max(dp[crt^1][3] + 1, dp[crt^1][2]);
+        dp[crt][3] = dp[crt^1][3];
+      } else {
+        dp[crt][0] = dp[crt^1][0];  
+        dp[crt][1] = max(dp[crt^1][0] + 1, dp[crt^1][1]);
+        dp[crt][2] = dp[crt^1][2];
+        dp[crt][3] = max(dp[crt^1][3] + 1, dp[crt^1][1] + 1);
+      }
+    }
+
+    cout << n - max({dp[crt][0], dp[crt][1], dp[crt][2], dp[crt][3]}) << '\n';
+  }
+
+  return 0;
+}