Create Longest Weird Subsequence.cpp

Author: MathProgrammer

Contests/Long Challenge/2012 03 March MARCH12/Programs/Longest Weird Subsequence.cpp

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+const int MAX_N = 2005, NO_OF_ALPHABETS = 26;
+int max_length[MAX_N][NO_OF_ALPHABETS][NO_OF_ALPHABETS];
+
+void solve()
+{
+    string S; 
+    cin >> S;
+    
+    int answer = 1;
+    
+    memset(max_length, 0, sizeof(max_length));
+    for(int alpha = 0; alpha < NO_OF_ALPHABETS; alpha++)
+    {
+        max_length[0][S[0] - 'a'][alpha] = 1; 
+        max_length[0][alpha][S[0] - 'a'] = 1;
+    }
+    
+    for(int i = 1; i < S.size(); i++)
+    {
+        for(int up_alpha = 0; up_alpha < NO_OF_ALPHABETS; up_alpha++)
+        {
+            for(int down_alpha = 0; down_alpha < NO_OF_ALPHABETS; down_alpha++)
+            {
+                
+               max_length[i][up_alpha][down_alpha] = max(
+                   max_length[i - 1][up_alpha][down_alpha], max_length[i][up_alpha][down_alpha]);
+                
+                int current_alpha = S[i] - 'a';
+                if(up_alpha <= current_alpha)
+                {   
+                    max_length[i][current_alpha][down_alpha] = max(max_length[i][current_alpha][down_alpha], 
+                        1 + max_length[i - 1][up_alpha][down_alpha]);
+                }
+                
+                if(down_alpha >= current_alpha)
+                {
+                    max_length[i][up_alpha][current_alpha] = max(max_length[i][up_alpha][current_alpha],
+                        1 + max_length[i - 1][up_alpha][down_alpha]);
+                }
+                
+                answer = max(answer, max_length[i][up_alpha][down_alpha]);
+            }
+        }
+    }
+    
+   cout << answer << "\n";
+}
+
+int main() 
+{
+	int no_of_test_cases; 
+	cin >> no_of_test_cases;
+	
+	while(no_of_test_cases--)
+	    solve();
+	    
+	return 0;
+}
+