Today I have done leetcode's March LeetCoding Challenge with cpp.

March LeetCoding Challenge 22

Description

Smallest String With A Given Numeric Value

The numeric value of a lowercase character is defined as its position (1-indexed) in the alphabet, so the numeric value of a is 1, the numeric value of b is 2, the numeric value of c is 3, and so on.

The numeric value of a string consisting of lowercase characters is defined as the sum of its characters' numeric values. For example, the numeric value of the string "abe" is equal to 1 + 2 + 5 = 8.

You are given two integers n and k. Return the lexicographically smallest string with length equal to n and numeric value equal to k.

Note that a string x is lexicographically smaller than string y if x comes before y in dictionary order, that is, either x is a prefix of y, or if i is the first position such that x[i] != y[i], then x[i] comes before y[i] in alphabetic order.

Example 1:

Input: n = 3, k = 27
Output: "aay"
Explanation: The numeric value of the string is 1 + 1 + 25 = 27, and it is the smallest string with such a value and length equal to 3.

Example 2:

Input: n = 5, k = 73
Output: "aaszz"

Constraints:

• 1 <= n <= 10^5
• n <= k <= 26 * n

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  string getSmallestString(int n, int k) {
    int zs = max<int>(ceil((k - n) / 25.0) - 1, 0);
    k -= zs * 26;
    n -= zs;
    return string(n - 1, 'a') + string(1, 'a'+ k - n) + string(zs, 'z');
  }
};

// Accepted
// 93/93 cases passed (24 ms)
// Your runtime beats 98.47 % of cpp submissions
// Your memory usage beats 63.02 % of cpp submissions (26.5 MB)