[LeetCode] 161. One Edit Distance

Given two strings S and T, determine if they are both one edit distance apart.

 Thought process:
Check if S and T are one insertion or replacement away.

 Solution:

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class Solution {
    public boolean isOneEditDistance(String s, String t) {
        if (s.equals(t)) {
            return false;
        }
        return isOneInsert(s, t) || isOneReplace(s, t);
    }
    
    private boolean isOneInsert(String s, String t) {
        if (Math.abs(s.length() - t.length()) != 1) {
            return false;
        }
        
        boolean inserted = false;
        int i = 0;
        int j = 0;
        
        while (i < s.length() && j < t.length()) {
            if (s.charAt(i) != t.charAt(j)) {
                if (inserted) {
                    return false;
                }
                
                inserted = true;
                if (s.length() < t.length()) {
                    j++;
                } else {
                    i++;
                }
            } else {
                i++;
                j++;
            }
        }
        return true;
    }
    
    private boolean isOneReplace(String s, String t) {
        if (s.length() != t.length()) {
            return false;
        }
        
        boolean replaced = false;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) != t.charAt(i)) {
                if (replaced) {
                    return false;
                }
                replaced = true;
            }
        }
        return true;
    }
}

Time complexity: O(n).
Location: Philadelphia, PA, USA

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