LeetCode - Isomorphic Strings

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Isomorphic Strings

2015.4.30 15:54

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

For example,
Given "egg", "add", return true.

Given "foo", "bar", return false.

Given "paper", "title", return true.

Note:
You may assume both s and t have the same length.

Solution:

　　Think about the string pair "abb" and "cdd". An isomorphic pair is like one-to-one mapping. So we use the basic priniciple: injective + surjective = bijective.

　　Check if the mapping from s to t is onto, and t to s as well. If both hold, they‘re isomorphic.

Accepted code:

 1 #include <cstring>
 2 using namespace std;
 3 
 4 class Solution {
 5 public:
 6     bool isIsomorphic(string s, string t) {
 7         return check(s, t) && check(t, s);
 8     }
 9 private:
10     bool check(string s, string t) {
11         char a[256];
12         
13         memset(a, 0, sizeof(a));
14         int i;
15         int n = s.length();
16         
17         for (i = 0; i < n; ++i) {
18             if (a[s[i]] == 0) {
19                 a[s[i]] = t[i];
20             }
21             s[i] = a[s[i]];
22         }
23         
24         return s == t;
25     }
26 };

LeetCode - Isomorphic Strings

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原文地址：http://www.cnblogs.com/zhuli19901106/p/4469153.html