LeetCode-in-Java

3106. Lexicographically Smallest String After Operations With Constraint

Medium

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:

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:

Input: s = “xaxcd”, k = 4

Output: “aawcd”

Explanation:

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

Example 3:

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.

Solution

public class Solution {
    public String getSmallestString(String s, int k) {
        char[] sArray = s.toCharArray();
        for (int i = 0; i < sArray.length; i++) {
            int distToA = cyclicDistance(sArray[i], 'a');
            if (distToA <= k) {
                sArray[i] = 'a';
                k -= distToA;
            } else if (k > 0) {
                sArray[i] = (char) (sArray[i] - k);
                k = 0;
            }
        }
        return new String(sArray);
    }

    private int cyclicDistance(char ch1, char ch2) {
        int dist = Math.abs(ch1 - ch2);
        return Math.min(dist, 26 - dist);
    }
}

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