Leetcode 400 Nth Digit

Leetcode 400 Nth Digit

using namespace std;class Solution {public:    int findNthDigit(int n) {    long numBit = 1;//long is necessary  1,2,3,4 bits of number    long interval = 9;//1*9 2*90 3*900 ……    long num = 1;//position     while(n > interval * numBit)    {        n -= interval * numBit;        numBit ++;        num += interval;        interval *= 10;    }    int i = (n - 1) / numBit;     i += num;     int j = (n - 1) % numBit;     return to_string(i)[j] - '0';//i is the number such as 80,if j == 0(0th bit),result is 8    }};