g0001_0100.s0065_valid_number.Solution.kt Maven / Gradle / Ivy

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Kotlin-based LeetCode algorithm problem solutions, regularly updated

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package g0001_0100.s0065_valid_number

// #Hard #String #2023_07_10_Time_151_ms_(100.00%)_Space_34.7_MB_(88.89%)

class Solution {
    fun isNumber(s: String): Boolean {
        if (s.isEmpty()) {
            return false
        }
        var eSeen = false
        var numberSeen = false
        var decimalSeen = false
        for (i in 0 until s.length) {
            val c = s[i]
            if (c.code >= 48 && c.code <= 57) {
                numberSeen = true
            } else if (c == '+' || c == '-') {
                if (i == s.length - 1 ||
                    i != 0 && s[i - 1] != 'e' && s[i - 1] != 'E'
                ) {
                    return false
                }
            } else if (c == '.') {
                if (eSeen || decimalSeen) {
                    return false
                }
                decimalSeen = true
            } else if (c == 'e' || c == 'E') {
                if (i == s.length - 1 || eSeen || !numberSeen) {
                    return false
                }
                eSeen = true
            } else {
                return false
            }
        }
        return numberSeen
    }
}