[leetcode]66. Plus One(Java)

https://leetcode.com/problems/plus-one/#/description

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

You may assume the integer do not contain any leading zero, except the number 0 itself.

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

思路：本道题中，给定的数组digits表示一个正整数。现在要把这个正整数+1.重点就是要考虑进位问题

从最后一位往前遍历，每一位如果是9，那么i-1。循环

如果当前为不为9，当前+1返回。

如果当前位为9，且i=0。新建一个数组res，长度为digits.length+1，第一位为1，其余为0。返回res

Java code:

package go.jacob.day623;public class Demo2 {public int[] plusOne(int[] digits) {int n = digits.length;        for(int i=n-1; i>=0; i--) {            if(digits[i] < 9) {                digits[i]++;                return digits;            }            digits[i] = 0;        }        //如果运行到这里，说明原数组重全部都为9.设最高位位1.其他位默认为0；        int[] newNumber = new int [n+1];        newNumber[0] = 1;        return newNumber;}}