PlusOne

Plus One

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.

Solution

直接从最后开始，处理进位

vector<int> plusOne(vector<int> &digits) {
	int i = digits.size() - 1;
	if (i < 0) {
		digits.push_back(1);
		return digits;
	}
	bool carry = true;
	while (i >= 0 && carry) {
		digits[i] += 1;
		if (digits[i] > 9) {
			digits[i] -= 10;
			carry = true;
		} else {
			carry = false;
		}
		i--;
	}
	if (carry) {
		digits.insert(digits.begin(), 1);
	}
	return digits;
}