[Resume the question] 66. Add one-Given a non-negative integer represented by a non-empty array of integers, add one to the number. The highest digit is stored in the first position of the array, and each element in the array only stores a single number.

Subject: 66. Plus one

Given a non-negative integer represented by a non-empty array of integers, add one to the number.

The highest digit is stored in the first position of the array, and each element in the array only stores a single number.

You can assume that in addition to the integer 0, this integer does not start with a zero.

answer:

int* plusOne(int* digits, int digitsSize, int* returnSize)
{
    
    
    int i=digitsSize-1;
    for(i;i>=0;i--)
    {
    
    
        // 如果当前位为1-8，直接+1即可返回
        if(digits[i]<9)
        {
    
    
            digits[i]++;
            *returnSize=digitsSize;
            return digits;
        }
        // 如果当前位为9，+1=10，所以当前位为0
        // 隐式进行+1操作
        else
            digits[i]=0;
    }
    // 程序走到这里，最高位产生进位，数组长度需要+1
    int* res=(int*)malloc(sizeof(int)*(digitsSize+1));
    // 最高位为1
    res[0] = 1;
    // 拷贝后面的数字到新的数组
    for(i=0;i<digitsSize;i++)
    {
    
    
        res[i+1]=digits[i];
    }
    *returnSize=digitsSize+1;
    return res;
}