手机键盘所有可能的英文组合

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九宫格样式

手机的上中文九宫格按键排布

输入:

一串从2到9的数字组成的字符串

输出:

所有可能的字母组合

思路:

单纯地以字节为单位,遍历输入的字符并循环添加可能的字符肯定是行不通的,因为这样复杂度会以n次幂指数增长.

解决方法就是保存结果字符串数组res,然后以res数组的长度为循环,往每一项后面加上新的字符,将其存入新的临时数组tmp中,再将tmp保存为新的res数组,最后res数组即为答案了.

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var map = {2:["a","b","c"],
           3:["d","e","f"],
           4:["g","h","i"],
           5:["j","k","l"],
           6:["m","n","o"],
           7:["p","q","r","s"],
           8:["t","u","v"],
           9:["w","x","y","z"],
          }
function make(str){
    var res = [""];
    for(let i =0; i<str.length; i++){
        var tmp = [];
        for(let j =0; j<res.length; j++){
            let num = str[i];
            for(let k=0; k<map[num].length; k++){
                tmp.push(res[j]+map[num][k])
            }
        }
        res = tmp
    }
    
    return res
}
//var str =readline();
//print(make(str))
str="996"
console.log(make(str))

结果

image