LeetCode [161] One Edit Distance

Given two strings s and t, determine if they are both one edit distance apart.

Note: 

There are 3 possiblities to satisify one edit distance apart:

1. Insert a character into s to get t
2. Delete a character from s to get t
3. Replace a character of s to get t

Example 1:

Input: s = "ab", t = "acb"
Output: true
Explanation: We can insert 'c' into s to get t.

Example 2:

Input: s = "cab", t = "ad"
Output: false
Explanation: We cannot get t from s by only one step.

Example 3:

Input: s = "1203", t = "1213"
Output: true
Explanation: We can replace '0' with '1' to get t.

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class Solution { public: bool isOneEditDistance(string s, string t) { int ns = s.size(); int nt = t.size(); if(abs(ns-nt)>1 || s==t) return false; if(ns==nt){ int ct = 0; for(int i=0; i<ns; ++i){ if(s[i]!=t[i]) ct++; if(ct>1) return false; } }else if(ns>nt){ int i=0, j=0; while(i<ns && j<nt){ if(s[i]!=t[j]){ if(i>j) return false; i++; }else{ i++; j++; } } }else{ return isOneEditDistance(t, s); } return true; } };