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Nth Digit in C++
Suppose we have one infinite integer sequence, we have to find the nth digit of this sequence. So if the input is 11, then the output will be 0 as if we place the numbers like 123456789101112, so the 11th digit is 0.
To solve this, we will follow these steps −
len := 0 and cnt := 9 and start := 1
while n > len * cnt
n := n – (len * cnt)
cnt := cnt * 10, start := start * 10
increase len by 1
start := start +(n - 1) / len
s := start as string
return s[(n – 1) mod len]
Example (C++)
Let us see the following implementation to get a better understanding −
#include <bits/stdc++.h>
using namespace std;
typedef long long int lli;
class Solution {
public:
int findNthDigit(int n) {
lli len = 1;
lli cnt = 9;
lli start = 1;
while(n > len * cnt){
n -= len * cnt;
cnt *= 10;
start *= 10;
len++;
}
start += (n - 1) / len;
string s = to_string(start);
return s[(n - 1) % len] - '0';
}
};
main(){
Solution ob;
cout << (ob.findNthDigit(11));
}Input
11
Output
0
Updated on: 29-Apr-2020
722 Views
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