Leetcode_plus-one(c++ and python updated)-优快云博客

本文提供了一种解决LeetCode上“加一”问题的有效方法。该问题要求将一个表示为数字数组的大数加一，并返回结果数组。文章中包含了C++及Python的实现代码，通过迭代数组并处理进位来完成加法操作。

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地址：http://oj.leetcode.com/problems/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.

思路：大数相加原理。用carry表示进位。40ms

参考代码：

class Solution {
public:
    vector<int> plusOne(vector<int> &digits) {
        int carry = 1, num = 0;
        vector<int>res;
        for(int i = digits.size()-1; i>=0; --i)
        {
            num = digits[i] + carry;
            if(num>9)
            {
                carry = 1;
                res.push_back(num-10);
            }
            else
            {
                carry = 0;
                res.push_back(num);
            }
        }
            
            if(carry)
                res.push_back(carry);
            
            reverse(res.begin(), res.end());
            return res;
        
    }
};

//SECOND TRIAL, 12ms
class Solution {
public:
    vector<int> plusOne(vector<int> &digits) {
        if(digits.empty())
            return digits;
        bool flag = false;
        int sz = digits.size();
        for(int i = 0; i<sz; ++i)
        {
            if(digits[i]!=9)
            {
                flag = true;
                break;
            }
        }
        if(!flag)
        {
            vector<int>ans(sz+1, 0);
            ans[0] = 1;
            return ans;
        }
        int carry = 1;
        for(int i = sz-1; i>=0; --i)
        {
            digits[i] += carry;
            if(digits[i]==10)
            {
                digits[i] = 0;
                carry = 1;
            }
            else
                break;
        }
        return digits;
    }
};

python：

class Solution:
    # @param digits, a list of integer digits
    # @return a list of integer digits
    def plusOne(self, digits):
        if not digits:
            return digits
        carry = 1
        for i in range(len(digits)-1, -1, -1):
            digits[i] += carry
            if digits[i] == 10:
                carry = 1
                digits[i] = 0
            else:
                return digits

        digits.insert(0, 1)
        return digits