Shortest Distance to a Character

Given a string s and a character c that occurs in s, return an array of integers answer where answer.length == s.length and answer[i] is the distance from index i to the closest occurrence of character c in s.

The distance between two indices i and j is abs(i - j), where abs is the absolute value function.

LeetCode Problem - 821

class Solution {
    public int[] shortestToChar(String s, char c) {
        int n = s.length(); // Length of the input string
        int[] answer = new int[n]; // Array to store the shortest distance to the character c
        int prev = Integer.MIN_VALUE / 2; // Initialize previous occurrence index to a very small value

        // First pass: from left to right
        for (int i = 0; i < n; i++) {
            // Update prev when the current character matches c
            if (s.charAt(i) == c) {
                prev = i;
            }
            // Calculate the distance from the current index to the last occurrence of c
            answer[i] = i - prev;
        }

        prev = Integer.MAX_VALUE / 2; // Initialize previous occurrence index to a very large value

        // Second pass: from right to left
        for (int i = n - 1; i >= 0; i--) {
            // Update prev when the current character matches c
            if (s.charAt(i) == c) {
                prev = i;
            }
            // Calculate the minimum distance from the current index to the nearest occurrence of c
            answer[i] = Math.min(answer[i], prev - i);
        }

        return answer; // Return the array with shortest distances
    }
}