[Leetcode] 408. Valid Word Abbreviation

initial

get index out of range error

def validWordAbbreviation(word: str, abbr: str) -> bool:
    """
    Check if abbreviation is valid for the given word.

    Time Complexity: O(n) where n is the length of abbr
    Space Complexity: O(1)
    """
    i,j=0,0
    while i<len(word) and j<len(abbr):
        number=""
        while abbr[j].isdigit():
            number+=abbr[j]
            j+=1
        if number:
            i+=int(number)
        if word[i]!=abbr[j]:
            return False
        i+=1
        j+=1
    return True

sol

def validWordAbbreviation(word: str, abbr: str) -> bool:
    """
    Check if abbreviation is valid for the given word.
    
    Time Complexity: O(n) where n is the length of abbr
    Space Complexity: O(1)
    """
    i = 0  # pointer for word
    j = 0  # pointer for abbr
    
    while i < len(word) and j < len(abbr):
        if abbr[j].isdigit():
            # Check for leading zero (invalid)
            if abbr[j] == '0':
                return False
            
            # Parse the complete number
            num = 0
            while j < len(abbr) and abbr[j].isdigit():
                num = num * 10 + int(abbr[j])
                j += 1
            
            # Skip 'num' characters in word
            i += num
        else:
            # Letter must match
            if abbr[j] != word[i]:
                return False
            i += 1
            j += 1
    
    # Both pointers should reach the end
    return i == len(word) and j == len(abbr)

complexity

n+m time 1 space