003_Longest_Substring_Without_Repeating_Characters.java

public class Solution {
    // example in leetcode book
    // public int lengthOfLongestSubstring(String s) {
    // 	boolean[] exist = new boolean[256];
    // 	int i = 0, maxLen = 0;
    // 	for (int j = 0; j < s.length(); j++) {
    // 		while (exist[s.charAt(j)]){
    // 			exist[s.charAt(i)] = false;
    // 			i++;
    // 		}
    // 		exist[s.charAt(j)] = true;
    // 		maxLen = Math.max(j - i + 1, maxLen);
    // 	}
    // 	return maxLen; 
    // }

    public int lengthOfLongestSubstring(String s) {
    	int[] charMap = new int[256];
    	Arrays.fill(charMap, -1);
    	int i = 0, maxLen = 0;
    	for (int j = 0; j < s.length(); j++) {
    		if (charMap[s.charAt(j)] >= i) {
    			i = charMap[s.charAt(j)] + 1;
    		}
    		charMap[s.charAt(j)] = j;
    		maxLen = Math.max(j - i + 1, maxLen);
    	}
    	return maxLen;
    }
}