string

Author: SamirPaulb

16_String/02. Backspace String Compare.py

@@ -0,0 +1,45 @@
+# https://leetcode.com/problems/backspace-string-compare/
+
+class Solution:
+    def backspaceCompare(self, s: str, t: str) -> bool:
+        i = len(s) - 1  # Traverse from the end of the strings
+        j = len(t) - 1 
+        # The number of backspaces required till we arrive at a valid character
+        bs = 0  # count of backspace for s
+        bt = 0  # count of backspace for t
+        
+        while i >= 0 or j >= 0:
+            while i >= 0:  # count bs
+                if s[i] == "#":
+                    bs += 1
+                    i -= 1
+                elif bs > 0 and s[i] != "#":
+                    bs -= 1
+                    i -= 1
+                else:
+                    break
+                    
+            while j >= 0:  # count bt
+                if t[j] == "#":
+                    bt += 1
+                    j -= 1
+                elif bt > 0 and t[j] != "#":
+                    bt -= 1
+                    j -= 1
+                else:
+                    break
+            # Also ensure that both the character indices are valid. If it is not valid,  it means that we are comparing a "#" with a valid character.
+            if i >= 0 and j < 0: return False
+            if i < 0 and j >= 0: return False
+            
+            if s[i] != t[j]: return False
+            
+            i -= 1
+            j -= 1
+        
+        
+        return True
+
+
+# Time Complexity: O(N)
+# Space Complexity: O(1)