📚 3.电话号码的字母组合

💻 代码实现

/**
 * @url https://leetcode.cn/problems/letter-combinations-of-a-phone-number/description/
 */

function init(): Map<string, string> {
    let map = new Map()
    map.set("2", "abc")
    map.set("3", "def")
    map.set("4", "ghi")
    map.set("5", "jkl")
    map.set("6", "mno")
    map.set("7", "pqrs")
    map.set("8", "tuv")
    map.set("9", "wxyz")
    return map
}
function letterCombinations(digits: string): string[] {
    const result: string[] = []
    const map = init()
    const dfs = (path: string[], idx: number) => {
        if (path.length === digits.length) {
            result.push(path.join(""))
            return
        }
        const str = map.get(digits[idx])
        for (let i = 0; i < str!.length; i++) {
            path.push(str![i])
            dfs(path.concat([]), idx + 1)
            path.pop()
        }
    }
    dfs([], 0)
    return result.filter((_str) => _str !== "")
}
// console.log(letterCombinations("23"))