Leet Code3 查找字符串中最长不重复的字符

Leet code3

Longest Substring Without Repeating Characters

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

---

思路：把字符串散列到一个table里面，字符串的assic码为数组的下标，比如a=97,如果没有遇到相同字符，每扫描一个 table中的字符 value+1；如果遇到重复 repeat+1； 最后end-repeat+1为 max的值。

import java.util.Arrays;

public class Solution {
public static void main(String[] args) {
    Solution solution = new Solution();
    solution.find();
}

public void find() {
    String s = "abcabcdefgh";
    int repeat = 0;
    int end = 1;
    int max = 1;
    int[] countstable = new int[255];
    Arrays.fill(countstable, -1);
    while (end < s.length()) {
        if (countstable[s.charAt(end)] >= repeat) {
            repeat = countstable[s.charAt(end)] + 1;
        }

        countstable[s.charAt(end)] = end;
        max = Math.max(max, end - repeat + 1);
        end++;
    }
    System.out.println(max);


}
}