66-加一

LeetCode 66. Plus One

LeetCode-66

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].

method

设置进位为1，每次更新进位，如果进位为0，就可以直接返回

vector<int> plusOne(vector<int>& digits) {
    int carry = 1;
    for (int i = digits.size() - 1; i >= 0; i--) {
        if (carry == 0) return digits;
        int sum = digits[i] + carry;
        digits[i] = sum % 10;
        carry = sum / 10;
    }
    if (carry) {    // 需要增加一位
        digits.push_back(0);
        digits[0] = 1;
    }
    return digits;
}