[daily training] 66 add one-tenth

subject

Given a by Integers Composed of Non empty The nonnegative integer represented by an array , Add one to the number .

The highest digit is placed at the top of the array , Each element in the array stores only a single number .

You can assume that except for integers 0 outside , This integer will not start with zero .

Example 1：
Input ：digits = [1,2,3]
Output ：[1,2,4]
explain ： Input array represents number 123.

Example 2：
Input ：digits = [4,3,2,1]
Output ：[4,3,2,2]
explain ： Input array represents number 4321.

Example 3：
Input ：digits = [0]
Output ：[1]

Tips ：
1 <= digits.length <= 100
0 <= digits[i] <= 9

Code

package dayLeetCode;

public class dayleetcode66 {
    
    /** *  The key is to deal with 9 * （1） The last one is not 9 Words , direct +1 * （2） The last few are 9 Words , Find the first non from back to front 9 The elements of , Put it +1, And then 9 Set all 0 * （3） All is 9 Words , Expand , Add a... At the top 1 * @param digits * @return */
    public int[] plusOne(int[] digits) {
    
        int n = digits.length;
        for (int i = n -1; i >= 0 ; i--) {
    
            if (digits[i] != 9){
    
                digits[i]++;
                for (int j = i + 1; j < n; j++){
    
                    digits[j] = 0;
                }
                return digits;
            }
        }


        digits = new int[n + 1];
        digits[0]  = 1;
        return digits;
    }

    public static void main(String[] args) {
    
        dayleetcode66 obj = new dayleetcode66();
        System.out.println(obj.plusOne(new int[]{
    1, 2, 3}));
    }
}