题目描述

从1到n整数中1出现的次数

样例

12
5

C++ 代码

class Solution {
public:
    int numberOf1Between1AndN_Solution(int n) {
        int count = 0;
        for (int i = 1; i <= n; i *= 10) {
            int a = n / i,b = n % i;
            count += (a + 8) / 10 * i + ((a % 10 == 1) ? b + 1 : 0);
        }
        return count;
    }