题目

Given a string containing just the characters ‘(’, ‘)’, ‘{’, ‘}’, ‘[’ and ‘]’, determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.

Note that an empty string is also considered valid.

就是要判断括号的顺序是否是正确的。

解法

解法1

func isValid(s string) bool { //这个解法用到了acsii值
	if len(s) == 0 {
		return true
	}

	left := make([]int, 1)
	left[0] = int(s[0])
	for i := 1; i < len(s); i++ {
		a := int(s[i])
		if len(left) == 0 {
			left = append(left, a)
			continue
		}
		if a-left[len(left)-1] != 1 && a-left[len(left)-1] != 2 {
			left = append(left, a)
		} else {
			left = left[:len(left)-1]
		}
	}

	if len(left) == 0 {
		return true
	} else {
		return false
	}
}

总结

解法1里面，我们使用的ascii码来判断，括号的顺序是否是对的。但是要注意的是，用ascii码来判断是有前提的，就是题目里面说了字符串只会出现这6个字符，不会出现其他的字符。不然这样的判断是不对的。