<p>Given an integer <code>n</code>, return the <code>n<sup>th</sup></code> digit of the infinite integer sequence <code>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...]</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> n = 3
<strong>Output:</strong> 3
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 11
<strong>Output:</strong> 0
<strong>Explanation:</strong> The 11<sup>th</sup> 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.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>

class Solution {
public:
    int findNthDigit(int n) {
        long long int pre=9,c=1,digits=9,l=0;
        while(1){
            if(n>digits)
                n=n-digits;
            else{
                // digits needed n
                int k=n/c;
                if(n%c)
                    k++;
                int ll=l+k;
                string cc=to_string(ll);
                int g=(n%c-1+c)%c;
                return cc[g]-'0';
                   // 

            }
            long long next=pre*10+9;
            l=pre;
            c=c+1;
            digits=(next-pre)*c;
            pre=next;
        }
        return 0;
    }
};
7300