Smallest String With A Given Numeric Value (C++ has the smallest string with a given value)

Problem-solving ideas:

(1) Back to front, greedy selection, recursive solution

class Solution {
public:
    string getSmallestString(int n, int k) {
        if(n==0) return "";
        if(k-(n-1)>=26) return getSmallestString(n-1,k-26)+'z';
        else if(k-(n-1)>=1 && k-(n-1)<26) return getSmallestString(n-1,n-1)+(char)('a'+k-(n-1)-1);
        else return "";
    }
};