具有给定数值的最小字符串 #23

 // 先全部置为a 然后从后面开始 加z 
var getSmallestString = function(n, k) {
    let obj = {
        1: 'a',
        2: 'b',
        3: 'c',
        4: 'd',
        5: 'e',
        6: 'f',
        7: 'g',
        8: 'h',
        9: 'i',
        10: 'j',
        11: 'k',
        12: 'l',
        13: 'm',
        14: 'n',
        15: 'o',
        16: 'p',
        17: 'q',
        18: 'r',
        19: 's',
        20: 't',
        21: 'u',
        22: 'v',
        23: 'w',
        24: 'x',
        25: 'y',
        26: 'z',
    }
    let arr = new Array(n).fill('a')
    let sum = n
    let index = arr.length - 1
    if (n === k) return arr.join('')
    while (k - sum > 25) {
        arr[index] = 'z'
        index--
        sum += 25
    }
    let temp = k - sum + 1
    arr[index] = obj[temp]
    return arr.join('')
  };