思想

1: 固定左边界, 移动右边界, 每次遇到重复字符, 开始计算最长字串
2: 左边界开始向左移动, 直到消掉重复字符,然后执行1

代码

func lengthOfLongestSubstring(s string) int {

length := len(s)

mapStr := make(map[byte]int, 0)
start := 0
end := 0
longnum := 0

for start < length {
    for ; end < length; end++{
        mapStr[s[end]]++
        if v, _:= mapStr[s[end]]; v == 2{
            break
        }
    }

    if longnum < end - start {
        longnum = end -start
    }

    i := start
    for ;i < end; i++ {
        mapStr[s[i]]--
        if  mapStr[s[i]] == 1{
            break
        }
    }
    start = i +1
    end++
}

return longnum

}