题解 | #牛群名字覆盖#

package main

import "math"

func minWindow(s string, t string) string {
	mymap := make(map[rune]int)
	copymap := make(map[rune]int)
	count := 0
	for _, v := range t {
		mymap[v]++
		copymap[v]++
		count++
	}
	l, r := -1, -1
	visitmap := make(map[rune]int)
	minlength := math.MaxInt
	result := ""
	for i, v := range s {

		if mymap[v] != 0 {
			if l == -1 {
				l = i
			}
			mymap[v]--
			count--

		}
		if l != -1 {
			visitmap[v]++
		}
		if count == 0 {
			r = i
			for j := l; j <= r; j++ {
				now := rune(s[j])
				visitmap[now]--
				l++
				if visitmap[now] < copymap[now] {
					break
				}
			}
			l--
			temp := s[l : r+1]
			if len(temp) < minlength {
				minlength = len(temp)
				result = temp
			}

			mymap[rune(s[l])]++
			count++

			l++
			for l <= r && copymap[rune(s[l])] == 0 {
				visitmap[rune(s[l])]--
				l++

			}

		}

	}

	if l == -1 || r == -1 {
		return ""
	}
	return result

}