README_EN.md

66. Plus One

中文文档

Description

Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer.

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contains a single digit.

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

 

Example 1:

Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.

Example 2:

Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.

Example 3:

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

 

Constraints:

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

Solutions

Python3

class Solution:
    def plusOne(self, digits: List[int]) -> List[int]:
        n = len(digits)
        for i in range(n - 1, -1 , -1):
            digits[i] += 1
            digits[i] %= 10
            if digits[i] != 0:
                return digits
        return [1] + digits

Java

class Solution {
    public int[] plusOne(int[] digits) {
        int n = digits.length;
        for (int i = n - 1; i >= 0; --i) {
            ++digits[i];
            digits[i] %= 10;
            if (digits[i] != 0) {
                return digits;
            }
        }
        digits = new int[n + 1];
        digits[0] = 1;
        return digits;
    }
}

JavaScript

/**
 * @param {number[]} digits
 * @return {number[]}
 */
var plusOne = function (digits) {
    for (let i = digits.length - 1; i >= 0; --i) {
        ++digits[i];
        digits[i] %= 10;
        if (digits[i] != 0) {
            return digits;
        }
    }
    return [1, ...digits];
};

C++

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        for (int i = digits.size() - 1; i >= 0; --i)
        {
            ++digits[i];
            digits[i] %= 10;
            if (digits[i] != 0) return digits;
        }
        digits.insert(digits.begin(), 1);
        return digits;
    }
};

Go

func plusOne(digits []int) []int {
	n := len(digits)
	for i := n - 1; i >= 0; i-- {
		digits[i]++
		digits[i] %= 10
		if digits[i] != 0 {
			return digits
		}
	}
	return append([]int{1}, digits...)
}

...