Merge pull request #103 from dsrao711/issue_101

Python solutions of String Problems in DSA-450

Author: smv1999

DSA 450 GFG/CountAndSay.py

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+# Problem : https://leetcode.com/problems/count-and-say/
+
+# Input: n = 4
+# Output: "1211"
+# Explanation:
+# countAndSay(1) = "1"
+# countAndSay(2) = say "1" = one 1 = "11"
+# countAndSay(3) = say "11" = two 1's = "21"
+# countAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"
+
+# Initialize counter = 1 to store the count of every element 
+# Initialize o/p string as ret = ""
+# If the previous element in the string is equal to the current element in the string , increament the counter
+# else Concatenate the count and the previous element of the string in ret
+
+# Return ret
+
+class Solution:
+    def countAndSay(self, n):
+        if (n == 1):
+            return ("1")
+        
+        s = self.countAndSay(n-1)
+        
+        ret = ""
+        cnt = 1
+        i = 1
+        while i < len(s) + 1:
+            if i < len(s) and s[i] == s[i-1]:
+                cnt += 1
+            else:
+                ret += str(cnt) + str(s[i-1])
+                cnt = 1
+            i += 1
+            
+        return (ret)

DSA 450 GFG/PrintAnagrams.py

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+
+# Problem : https://practice.geeksforgeeks.org/problems/print-anagrams-together/1
+
+
+# Input:
+# N = 5
+# words[] = {act,god,cat,dog,tac}
+# Output: 
+# god dog
+# act cat tac
+# Explanation:
+# There are 2 groups of
+# anagrams "god", "dog" make group 1.
+# "act", "cat", "tac" make group 2.
+
+from collections import defaultdict
+
+def Anagrams(words,n):
+    '''
+    words: list of word
+    n:      no of words
+    return : list of group of anagram {list will be sorted in driver code (not word in grp)}
+    '''
+    
+    #code here
+    anagrams = defaultdict(list)
+    
+    for word in words:
+        anagrams["".join(sorted(word))].append(word)
+  
+    return anagrams.values()
+    
+
+#  Driver Code 
+
+if __name__ =='__main__':
+    t= int(input())
+    for tcs in range(t):
+        n= int(input())
+        words=input().split()
+        
+        ans=Anagrams(words,n)
+        
+        for grp in sorted(ans):
+            for word in grp:
+                print(word,end=' ')
+            print()
+
+
+
+# Used default dict from collections module . It does not raise key value error