SmallestAdjacent

public class SmallestAdjacent {
	
	// first version, convert int x to a string
	public static int solutionString(int x){
		String input = String.valueOf(x);
		int min = Integer.MAX_VALUE;
		
		for (int i = 0; i < input.length() - 1; i++) {
			int index = (input.charAt(i) - '0' < input.charAt(i + 1) - '0') ? i : i + 1;
			String result = input.substring(0, index) + input.substring(index + 1);
			int res = Integer.parseInt(result);
			min = res > min ? min : res;
		}
		return min;
	}
	
	public static void main(String[] args) {
		System.out.println(solutionString(233614));
	}
	
	// second solution, manipulate of a number
	public static int solution(int x){
		int min = Integer.MAX_VALUE;
		
		// copy the digits to an array
		ArrayList<Integer> digits = new ArrayList<>();
		int input = x;
		while (input > 0) {
			digits.add(input % 10);
			input /= 10;
		}
		
		// for each pair of adjacent digits
		for (int i = 0; i < digits.size() - 1; i++) {
			int removedIndex = digits.get(i) > digits.get(i + 1) ? i + 1 : i;
			int replacedInt = reconstruct(x, removedIndex);
			min = replacedInt > min ? min : replacedInt;
		}
		
		return min;
	}
	
	private static int reconstruct(int x, int removedIndex) {
		// this will not overflow since it must be less than the given integer x
		int afterPower = (int) Math.pow(10, removedIndex);
		// concatenate the digits before and after the removed digit
		return x / afterPower / 10 * (int) afterPower + x % afterPower;
	}
}