Plus One

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66.Plus One

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:

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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:

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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:

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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].

个人解答：

时间复杂度：O(n)

空间复杂度：O(n)

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vector<int> plusOne(vector<int>& digits) {
    int digits_size = digits.size();
    if (digits[digits_size - 1] != 9) {
        digits[digits_size - 1] += 1;
        return digits;
    }
    else {
        if (digits_size == 1)return{ 1,0 };
        int index = digits_size - 2;
        digits[digits_size - 1] = 0;
        while (digits[index] == 9) {
            digits[index] = 0;
            index--;
            if (index == -1) {
                vector<int> digits(digits_size + 1);
                digits[0] = 1;
                while (digits_size > 0) {
                    digits[digits_size] = 0;
                    digits_size--;
                }
                return digits;
            }
        }
        digits[index] += 1;
        return digits;
    }
}