leetcode-剑指44-OK

标签：int   position   c++   find   public   printf   etc   dig   osi   

// language C with STL(C++)
// 剑指44
// https://leetcode-cn.com/problems/shu-zi-xu-lie-zhong-mou-yi-wei-de-shu-zi-lcof/
// 同主站400题
// https://leetcode-cn.com/problems/nth-digit/


class Solution {
public:
    long power_10(long i){
        long res = 1;
        while(i>0){
            res*=10;
            i--;
        }
        return res;
    }
    long sum(long i){
        return ((9*i-1)*power_10(i+1)+10)/90;
    }
    int findNthDigit(int n){
        if(n<1)
            return n;
        int i = 1;
        while(n > sum(i))
            i++;
        i -=1;
        // printf("%d-", i);
        n -= sum(i);
        // printf("%d-", n);
        int position = n%(i+1); //正数第几个数位
        // printf("%d", position);
        n = power_10(i) + n/(i+1);
        // printf("%d-", n);   // 第几个数
        if(position==0){
            n-=1;
            position = 1;
        }
        else
            position = i+2-position;
        n = n/power_10(position-1);
        return n%10;
    }
};

leetcode-剑指44-OK

标签：int   position   c++   find   public   printf   etc   dig   osi   

原文地址：https://www.cnblogs.com/gallien/p/14379155.html