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The Celebrity Problem - GFG/README.md

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+# The Celebrity Problem
+## Medium 
+<div class="problem-statement">
+                <p></p><p><span style="font-size:18px">A celebrity is a person who is known to all but does not know anyone at a party. If you go to a party of N people, find if there is a celebrity in the party or not.<br>
+A square NxN matrix M[][] is used to represent people at the party such that if an element of row i and column j &nbsp;is set to 1 it means ith person knows jth person. Here M[i][i] will always be 0.<br>
+<strong>Note:</strong> Follow 0 based indexing.</span><br>
+&nbsp;</p>
+
+<p><strong><span style="font-size:18px">Example 1:</span></strong></p>
+
+<pre><span style="font-size:18px"><strong>Input:</strong>
+N = 3
+M[][] = {{0 1 0},
+         {0 0 0}, 
+         {0 1 0}}
+<strong>Output:</strong> 1
+<strong>Explanation: </strong>0th and 2nd person both
+know 1. Therefore, 1 is the celebrity. </span></pre>
+
+<p><br>
+<span style="font-size:18px"><strong>Example 2:</strong></span></p>
+
+<pre><span style="font-size:18px"><strong>Input:</strong>
+N = 2
+M[][] = {{0 1},
+         {1 0}}
+<strong>Output:</strong> -1
+<strong>Explanation: </strong>The two people at the party both
+know each other. None of them is a celebrity.</span></pre>
+
+<p><br>
+<span style="font-size:18px"><strong>Your Task:</strong><br>
+You don't need to read input or print anything. Complete the function <strong>celebrity()</strong> which takes the matrix M and its size N as input parameters and returns the index of the celebrity. If no such celebrity is present, return -1.</span></p>
+
+<p><br>
+<span style="font-size:18px"><strong>Expected Time Complexity:</strong> O(N)<br>
+<strong>Expected Auxiliary Space:</strong> O(1)</span></p>
+
+<p><br>
+<span style="font-size:18px"><strong>Constraints:</strong><br>
+2 &lt;= N &lt;= 3000<br>
+0 &lt;= M[][] &lt;= 1</span></p>
+ <p></p>
+            </div>