8
is the lucky number of Xiaojiu. Xiaojiu wants to know how many numbers in the numbers 1~n
contain 8
.
Notice
1 <= n <= 1000000
Example
Given n = 20
, return 2
.
Explanation:
Only 8,18 contains 8.
Given n = 100
, return 19
.
Explanation:
8,18,28,38,48,58,68,78,80,81,82,83,84,85,86,87,88,89,98 contains 8.
解题思路:
从1到n遍历,把其中每一个数拆分数字,一旦发现有8存在即count++,跳出,继续下一个数字的考察。
注意在遍历里面不能直接用i来拆分,这样会引起遍历始终从零开始,所以需要复制出来操作,i仅用作次数循环。
class Solution { public: /** * @param n: count lucky numbers from 1 ~ n * @return: the numbers of lucky number */ int luckyNumber(int n) { // Write your code here int count = 0; for(int i=1;i<=n;i++) { int t=i; while(t) { if(t%10 == 8) { count++; break; } t = t/10; } } return count; } };