力扣题库3.无重复字符的最长子串

给定一个字符串 s ，请你找出其中不含有重复字符的 最长子串 的长度。

Swift

/*
 * 滑动窗口法
 */
func lengthOfLongestSubstring(_ s: String) -> Int {
        
        let strlen = s.count
        let chs: [Character] = Array(s)
    
        var map = [Character : Int]()
        var start = 0
        
        var maxLen: Int = 0
        for i in 0..<chs.count {
            let char = chs[i]
            if let preIdx = map[char] {
                start = max(start, preIdx+1)
            }
            
            map[char] = i;
            maxLen = max(maxLen, i-start+1)
            
            print(start, maxLen)
        }
        
        return maxLen
    }
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OC

/*
 * 滑动窗口法
 */
 - (NSInteger)lengthOfLongestSubstring:(NSString *)s {
    if (s.length < 2) {
        return s.length;
    }
    
    NSInteger strLen = s.length;
    NSInteger maxLen = 0;
    NSInteger start = 0;
    NSMutableDictionary *map = [NSMutableDictionary dictionary];
    
    for (NSInteger i=0; i