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leetcode算法题--表示数值的字符串

news 2025/7/16 19:22:13

原题链接：https://leetcode.cn/problems/biao-shi-shu-zhi-de-zi-fu-chuan-lcof/description/?envType=study-plan-v2&envId=coding-interviews

题目类型有点新颖，有限状态机

// CharType表示当前字符的类型
// State表示当前所处的状态
type State int
type CharType intconst (CHAR_SPACE CharType = iotaCHAR_POINTCHAR_NUMBERCHAR_ECHAR CHAR_SINGAL CHAR_INVALID
)func getType(ch byte) CharType {switch(ch){case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':return CHAR_NUMBERcase '.':return CHAR_POINTcase '+', '-':return CHAR_SINGAL
//        case ' ':
//            return CHAR_SPACEcase 'e', 'E':return CHAR_ECHAR} return CHAR_INVALID
}const (STATE_INIT State = iotaSTATE_INIT_POINTSTATE_INIT_SINGALSTATE_NUMBERSTATE_NUMBER_POINTSTATE_POINT_NUMBERSTATE_ECHARSTATE_ECHAR_NUMBERSTATE_ECHAR_SINGAL
)func isNumber(s string) bool {tranfer := map[State]map[CharType]State{STATE_INIT: {CHAR_SINGAL: STATE_INIT_SINGAL,CHAR_POINT: STATE_INIT_POINT,CHAR_NUMBER: STATE_NUMBER,}, STATE_INIT_POINT: {CHAR_NUMBER: STATE_POINT_NUMBER,},STATE_NUMBER: {CHAR_NUMBER: STATE_NUMBER,CHAR_POINT: STATE_NUMBER_POINT,CHAR_ECHAR: STATE_ECHAR,},STATE_INIT_SINGAL: {CHAR_POINT: STATE_INIT_POINT, CHAR_NUMBER: STATE_NUMBER, },STATE_ECHAR: {CHAR_SINGAL: STATE_ECHAR_SINGAL,CHAR_NUMBER: STATE_ECHAR_NUMBER,},STATE_NUMBER_POINT: {CHAR_NUMBER: STATE_POINT_NUMBER,CHAR_ECHAR: STATE_ECHAR, },STATE_POINT_NUMBER: {CHAR_NUMBER: STATE_POINT_NUMBER, CHAR_ECHAR: STATE_ECHAR, },STATE_ECHAR_NUMBER: {CHAR_NUMBER: STATE_ECHAR_NUMBER,}, STATE_ECHAR_SINGAL: {CHAR_NUMBER: STATE_ECHAR_NUMBER,},}state := STATE_INITss := strings.TrimSpace(s)for i := range ss {ch := ss[i]ty := getType(ch)if ty == CHAR_INVALID {return false}if st, ok := tranfer[state][ty]; ok {state = st} else {return false}}switch state {case STATE_NUMBER, STATE_POINT_NUMBER, STATE_NUMBER_POINT, STATE_ECHAR_NUMBER:return true}return false
}