Largest Merge Of Two Strings

Problem Description

You are given two strings word1 and word2. You want to construct a string merge in the following way: while either word1 or word2 are non-empty, choose one of the following options:

• If word1 is non-empty, append the first character in word1 to merge and delete it from word1.
• If word2 is non-empty, append the first character in word2 to merge and delete it from word2.

Return the lexicographically largest merge you can construct.

Key Insights

• The problem requires constructing a new string by choosing characters from two input strings based on lexicographical order.
• At each step, the decision to take a character from word1 or word2 depends on which string has the lexicographically larger remaining substring.
• A greedy approach is used where, at each step, the string that can produce a larger lexicographical outcome is chosen.

Space and Time Complexity

Time Complexity: O(n + m), where n is the length of word1 and m is the length of word2.
Space Complexity: O(n + m) for storing the resulting merge string.

Solution

The solution uses a greedy algorithm combined with two pointers to traverse the strings. By comparing the remaining substrings of word1 and word2, we decide which character to append to the merge string. The process continues until both strings are empty.

Code Solutions