Shortest Distance to a Character

class Solution {
    public int[] distanceToChar(String str, char target) {
        int length = str.length();
        int[] result = new int[length];
        int lastSeen = Integer.MIN_VALUE / 2;
    
        for (int i = 0; i < length; ++i) {
            if (str.charAt(i) == target) lastSeen = i;
            result[i] = i - lastSeen;
        }
    
        lastSeen = Integer.MAX_VALUE / 2;
        for (int i = length - 1; i >= 0; --i) {
            if (str.charAt(i) == target) lastSeen = i;
            result[i] = Math.min(result[i], lastSeen - i);
        }
    
        return result;
    }
}

The Java solution provided outlines an efficient method to calculate the shortest distance from each character in a given string to a specific target character. The function distanceToChar takes a string and a character as input and returns an array of integers where each element represents the minimum distance to the nearest occurrence of the target character.

• The function initializes an array result of the same length as the input string, to store the distances.
• It uses a variable lastSeen to keep track of the last occurrence index of the target character.
• The first loop iterates through the string from the start to end, updating lastSeen whenever the target character is found and calculating the distance from the current index to lastSeen.
• The second loop iterates from the end of the string back to the start. This ensures that each character in the string is compared with the nearest occurrence of the target character both before and after it.
• The minimum distance from each character to the target is then updated in the result array using the Math.min method.

This two-pass approach ensures that all possible directions are considered for determining the shortest distance to the target character, resulting in an efficient and comprehensive solution.