66. Plus One

🟢   🔖  数组 数学  🔗 LeetCode

题目

You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0's.

Increment the large integer by one and return the resulting array of digits.

Example 1:

Input: digits = [1,2,3]

Output: [1,2,4]

Explanation: The array represents the integer 123.

Incrementing by one gives 123 + 1 = 124.

Thus, the result should be [1,2,4].

Example 2:

Input: digits = [4,3,2,1]

Output: [4,3,2,2]

Explanation: The array represents the integer 4321.

Incrementing by one gives 4321 + 1 = 4322.

Thus, the result should be [4,3,2,2].

Example 3:

Input: digits = [9]

Output: [1,0]

Explanation: The array represents the integer 9.

Incrementing by one gives 9 + 1 = 10.

Thus, the result should be [1,0].

Constraints:

• 1 <= digits.length <= 100
• 0 <= digits[i] <= 9
• digits does not contain any leading 0's.

题目大意

给定一个由整数组成的非空数组所表示的非负整数，在该数的基础上加一。最高位数字存放在数组的首位， 数组中每个元素只存储单个数字。你可以假设除了整数 0 之外，这个整数不会以零开头。

解题思路

• 给出一个数组，代表一个十进制数，数组的 0 下标是十进制数的高位。要求计算这个十进制数加一以后的结果。
• 简单的模拟题。从数组尾部开始往前扫，逐位进位即可。最高位如果还有进位需要在数组里面第 0 位再插入一个 1 。

代码

/**
 * @param {number[]} digits
 * @return {number[]}
 */
var plusOne = function (digits) {
	for (let i = digits.length - 1; i >= 0; i--) {
		if (digits[i] < 9) {
			digits[i] += 1;
			return digits;
			// starting from extreme right--> if array[i] is less than 9 means can be added with 1
			// i.e. [ 5,8 ]-->[ 5,9 ] or
			//      [ 9,4 ]-->[ 9,5 ] or
			//      [ 6,0 ]-->[ 6,1 ]
			// and will directly return array
		}
		digits[i] = 0;
		// if array[i] is not less than 9, means it have to be 9 only then digit is changed to 0,
		// and we again revolve around loop to check for number if less than 9 or not
		// i.e. [ 5,9 ]-->[ 5,0 ]-loop->[ 6,0 ] or
		//      [ 1,9,9 ]-->[ 1,9,0 ]-loop->[ 1,0,0 ]-loop->[ 2,0,0 ]
		// and will directly return array
	}
	digits.unshift(1);
	// if all number inside array are 9
	// i.e. [ 9,9,9,9 ] than according to above loop it will become [ 0,0,0,0 ]
	// but we have to make it like this [ 9,9,9,9 ]-->[ 1,0,0,0,0 ]
	return digits;
};

相关题目

相关题目

• 43. 字符串相乘
• 67. 二进制求和
• 🔒 Plus One Linked List
• 989. 数组形式的整数加法
• 2571. 将整数减少到零需要的最少操作数

- [43. 字符串相乘](https://leetcode.com/problems/multiply-strings)
- [67. 二进制求和](https://leetcode.com/problems/add-binary)
- [🔒 Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list)
- [989. 数组形式的整数加法](https://leetcode.com/problems/add-to-array-form-of-integer)
- [2571. 将整数减少到零需要的最少操作数](https://leetcode.com/problems/minimum-operations-to-reduce-an-integer-to-0)