66. Plus One

题目

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

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

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

思路

弄个临时变量记进位,从第n-1位按照加法开始依次加就好了。

代码

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//C++ Solution
vector<int> plusOne(vector<int>& digits) {
int flag = 1;
for(int i = digits.size()-1;i>=0;i--) {
int temp = digits[i] + flag;
if(temp<10) {
digits[i] = temp;
flag = 0;
break;
}
else {
digits[i] = temp%10;
flag = 1;
}
}
if(flag == 1) {
digits.insert(digits.begin(),1);
}
return digits;
}

然后Discuss看到了个比较吊的

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//C++ Solution
void plusone(vector<int> &digits)
{
int n = digits.size();
for (int i = n - 1; i >= 0; --i)
{
if (digits[i] == 9)
{
digits[i] = 0;
}
else
{
digits[i]++;
return;
}
}
digits[0] =1;
digits.push_back(0);

}
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