Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...
Note: n is positive and will fit within the range of a 32-bit signed integer (n < 2^31).
Example 1:
Input: 3
Output: 3
Example 1:
Input: 11
Output: 0
Explanation:
The 11th digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...
is a 0, which is part of the number 10.
Solution:
class Solution {
public:
int findNthDigit(int n) {
if(n <= 9) return n;
int s=1,i=1,j=9,base=0;
while(n>j && s<8){
s++;
i*=10;
j=j+s*i*9;
}
if(s == 8 && n > j){
s++;
i*=10;
base = j;
}else{
base = j - s * i * 9;
}
int offset = n - base - 1;
int target = i + offset / s;
int index = offset % s;
return to_string(target)[index] - '0';
}
};
