<p>Given an integer <code>n</code>, return <em>the number of positive integers in the range </em><code>[1, n]</code><em> that have <strong>at least one</strong> repeated digit</em>.</p>

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

<pre>
<strong>Input:</strong> n = 20
<strong>Output:</strong> 1
<strong>Explanation:</strong> The only positive number (&lt;= 20) with at least 1 repeated digit is 11.
</pre>

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

<pre>
<strong>Input:</strong> n = 100
<strong>Output:</strong> 10
<strong>Explanation:</strong> The positive numbers (&lt;= 100) with atleast 1 repeated digit are 11, 22, 33, 44, 55, 66, 77, 88, 99, and 100.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> n = 1000
<strong>Output:</strong> 262
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution {
public:
    int dp[4000][25][3][3][3];
    int solve(string &n , int i , int mask1 ,int cnt,int tight , int h){
        if(i==n.size()){
            return cnt;
        }
        if(dp[mask1][i][tight][cnt][h] != -1){
            return dp[mask1][i][tight][cnt][h];
        }
        int limit = tight? n[i] -'0' :9;
        int ans = 0 ;       
        for(int d =0 ; d<= limit ; d++){
         if(d== 0){
            if(h){
            if(mask1&(1<<d)){
             ans+= solve(n, i+1 , mask1 ,1 , tight&(d==(n[i] -'0')) , ( h|(d>0)));
            }
            else{
            ans+= solve(n , i+1 , mask1|(1<<d) , cnt ,tight&(d==(n[i] -'0')) ,(h|(d>0)));
            } 
           }
           else{
              ans+= solve(n , i+1 , mask1 , cnt , tight&(d==(n[i] -'0')) , (h|(d>0)));
           }
         }
          else if(mask1&(1<<d)){
             ans+= solve(n, i+1 , mask1 ,1 , tight&(d==(n[i] -'0')) ,  (h|(d>0)));
          }
          else{
            ans+= solve(n , i+1 , mask1|(1<<d) , cnt ,tight&(d==(n[i] -'0')) ,(h|(d>0)));
          }
        }
    return dp[mask1][i][tight][cnt][h] = ans; 
    }
    int numDupDigitsAtMostN(int n) {
    string s= to_string(n);
    memset(dp  , - 1, sizeof(dp));
     return solve(s, 0 , 0 , 0 , 1 ,0 );
    }
};
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