Plus One

问题描述

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.

解决方案

public class Solution {
	public int[] plusOne(int[] digits) {
		int length = digits.length;
		boolean addOneDigit = true;
		for( int digit : digits ) {
			if( digit != 9 ) {
				addOneDigit = false;
				break;
			}
		}
		int[] result = addOneDigit ? new int[length + 1] : new int[length];

		if( addOneDigit ) {
			result[0] = 1;
			for( int i = 1; i < length; ++i ) {
				result[i] = 0;
			}
			return result;
		}

		int add = 1;
		for( int i = length - 1; i >= 0; --i ) {
			result[i] = digits[i] + add;
			if( add == 1 ){
				add = 0;
			}
			if( result[i] == 10 ) {
				result[i] = 0;
				add = 1;
			}
		}
		return result;
	}
}