1. Topic
Given a non-negative integer represented by a non-empty array of integers, add one to the number .
The highest digit is stored at the head of the array, and each element in the array stores only a single number.
You can assume that this integer will not start with a zero other than the integer 0.
2. Examples
Example 1:
Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The input array represents the digit 123.
Example 2:
Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The input array represents the digit 4321.
Example 3:
input: digits = [0]
output: [1]
3. Ideas
This question looks relatively simple, but there are also pitfalls.
The first point, when the last digit is 9, a carry is required when adding one.
Secondly, when the first digit is 9, adding one needs to recreate a new array, and assign a value of 1 to the first digit of the new array.
4. Code
class Solution {
public int[] plusOne(int[] digits) {
if (digits.length==1 &&digits[0]==0){
digits[0] = 1;
}else {
digits[digits.length-1]+=1;
}
for (int i= digits.length-1;i>=0;i--){
if (digits[i]==10){
if (digits.length ==1 || i == 0){
digits = new int[digits.length+1];
digits[0]=1;
break;
}
digits[i] =0;
digits[i-1]+=1;
}
}
return digits;
}
}Will it? Try to challenge the next question! ♪(＾∀＾●)ﾉｼ(●´∀｀)♪
LeetCode 150 classic interview questions -- plus one (simple)_Alphamilk's Blog-CSDN Blog