p205

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LeetCode p205 Isomorphic Strings 题解

1.题目：

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.

题意：

输入两个字符串，判断一个是否他们是否同构，及字符能够完全映射。

2.解题思路:

记录每个字符上次出现的位置，比较。
// ASCII 256个

3.代码

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public class Solution {
    public boolean isIsomorphic(String s, String t) {
        if (s.length() != t.length())
			return false;
		int[] ak = new int[256 * 2];
		for (int i = 0; i < s.length(); i++) {
			if (ak[s.charAt(i)] != ak[t.charAt(i) + 256])
				return false;
			ak[s.charAt(i)] = i + 1; // 因为初始化全为0这里加一区分
			ak[t.charAt(i) + 256] = i + 1;
		}
		return true;
    }
}

4.一些总结：