87 lines
2.7 KiB
C++
87 lines
2.7 KiB
C++
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// Source : https://oj.leetcode.com/problems/one-edit-distance/
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// Author : Hao Chen
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// Date : 2014-12-03
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/*
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* Given two strings S and T, determine if they are both one edit distance apart.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <iostream>
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#include <string>
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using namespace std;
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/*
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* Notes:
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*
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* If you try to use the Dynamic Program Algorithm, just like the `Edit Distance`,
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* Then, you will get `Memory Limit Error` or `Time Limit Error`.
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*
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* The Dynamic Program Algorithm which `Edit Distance` prolem used call `Wagner–Fischer Algorithm`
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* (refer to: http://en.wikipedia.org/wiki/Wagner%E2%80%93Fischer_algorithm)
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* Ths DP algorithm's time complexity is O(m*n), and the space complexity is O(m*n) as well,
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* You can optimized the space complexity to O(2*min(m,n)), but it still have `Time Limit Error`
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*
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* Fortunately, this problem just for the `One` edit distance, so, this is special case we can solve it by special way.
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*/
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bool isOneEditDistance(string s, string t) {
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int len_s = s.size();
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int len_t = t.size();
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if (len_s==0) return len_t==1;
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if (len_t==0) return len_s==1;
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switch (abs(len_s-len_t)) {
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case 0:
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{
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//if these two strings have same length.
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//it means - we cannot use `add` or `delete` edit methods, just use the `replace` method
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//So, just simply count the different char(s).
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int cnt=0;
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for (int i=0; i<len_s; i++){
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if(s[i]!=t[i]){
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cnt++;
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if(cnt>1) return false;
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}
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}
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return cnt==1;
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}
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case 1:
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{
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//if these two strings' length just have ONE difference.
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//it means - we only can use `delete` edit method to delete one char in longer string.
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//So, just remove one char in longer string, and check it whether equal to shorter string.
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string& ss = (len_s > len_t)? s : t;
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string& tt = (len_s < len_t)? s : t;
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for(int i=0; i<ss.size(); i++){
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string tmp = ss;
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if (ss.erase(i,1) == tt) {
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return true;
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}
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}
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return false;
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}
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default:
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return false;
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}
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return false;
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}
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int main(int argc, char** argv)
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{
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string s="ab", t="acb";
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if(argc>2){
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s = argv[1];
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t = argv[2];
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}
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cout << "s = \"" << s << "\" t = \"" << t << "\" : " << (isOneEditDistance(s,t) ? "true" : "false") << endl;
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return 0;
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}
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