3106. Lexicographically Smallest String After Operations With Constraint

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3106. Lexicographically Smallest String After Operations With Constraint

Description

You are given a string s and an integer k.

Define a function distance(s1, s2) between two strings s1 and s2 of the same length n as:

  • The sum of the minimum distance between s1[i] and s2[i] when the characters from 'a' to 'z' are placed in a cyclic order, for all i in the range [0, n - 1].

For example, distance("ab", "cd") == 4, and distance("a", "z") == 1.

You can change any letter of s to any other lowercase English letter, any number of times.

Return a string denoting the lexicographically smallest string t you can get after some changes, such that distance(s, t) <= k.

Example 1:

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Input: s = "zbbz", k = 3

Output: "aaaz"

Explanation:

Change `s` to `"aaaz"`. The distance between `"zbbz"` and `"aaaz"` is equal to `k = 3`.

Example 2:

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Input: s = "xaxcd", k = 4

Output: "aawcd"

Explanation:

The distance between "xaxcd" and "aawcd" is equal to k = 4.

Example 3:

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Input: s = "lol", k = 0

Output: "lol"

Explanation:

It's impossible to change any character as `k = 0`.

**Constraints:**

- `1 <= s.length <= 100`
- `0 <= k <= 2000`
- `s` consists only of lowercase English letters.

Hints/Notes

  • change as many letters to ‘a’ first, then append the remaining

Solution

Language: C++

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class Solution {
public:
    string getSmallestString(string s, int k) {
        int idx = 0;
        string res;
        while (idx < s.size()) {
            char c = s[idx];
            bool forward = true;
            int distance = min(c - 'a', 'z' - c + 1);
            if (k >= distance) {
                res += 'a';
                k -= distance;
            } else {
                res += c - k;
                k = 0;
            }
            idx++;
        }
        return res;
    }
};