Plus One

Description

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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.

题意理解

给你一个数字以顺序结构存储每一位的数字，并且首数字不为0例如

12345 means [1,2,3,4,5]   

对这个数字进行+1操作，返回计算结果值

解题思路

首先，数字存储是反向的，数字的高位在数组的地位，因此是反向遍历；
其次，设置一个进位，初始值为1，作为+1的数值，在遍历完成后判断进位标识符是否为1，若是，则在顺序结构的头部插入一个1

代码如下

 
vector plusOne(vector& digits) { 
    int carry = 1; 
    int len = digits.size(); 
    for (int i = len - 1; i >= 0; i–){ 
        int t = digits[i] + carry; 
        digits[i] = t % 10; 
        carry = t / 10; 
    } 
    if (carry != 0){ 
        digits.insert(digits.begin(), 1); 
    } 
    return digits; 
}