题解 | #NC329 电话号码的字母组合#

这道题考察的是回溯算法，而且是典型的回溯组合，没人用js提交，我来分享下我的代码

function phoneNumber( num ) {
    const map = {
    "2": "ABC",
    "3": "DEF",
    "4": "GHI",
    "5": "JKL",
    "6": "MNO",
    "7": "PQRS",
    "8": "TUV",
    "9": "WXYZ",
  }
    const res = []
    const temp = []
    let index = 0
    function way(index) {
        if(num.length === temp.length) {
            res.push(temp.join(""))
            return
        }
        let letter = map[num[index]]
        for(let i = 0; i < letter.length; ++i) {
            temp.push(letter[i])
            way(index+1)
            temp.pop()
        }
    }
    way(index)
    return res
}
module.exports = {
    phoneNumber : phoneNumber
};