stack

Author: imShubh03

Stack/H1/celebrity-Problem.cpp

@@ -0,0 +1,85 @@
+#include <bits/stdc++.h> 
+using namespace std;
+
+/* brute time:O(n^2) space:O(1)
+class Solution {
+public:
+    // Function to find if there is a celebrity in the party or not.
+    int celebrity(vector<vector<int>>& mat) {
+        int n = mat.size();
+        vector<int> knowMe(n, 0);
+        vector<int> Iknow(n, 0);
+        
+        // Iterate over the matrix to populate knowMe and Iknow arrays
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                if (mat[i][j] == 1) {
+                    knowMe[j]++;
+                    Iknow[i]++;
+                }
+            }
+        }
+        
+        // Check for a celebrity
+        for (int i = 0; i < n; i++) {
+            if (knowMe[i] == n - 1 && Iknow[i] == 0) {
+                return i;
+            }
+        }
+        
+        return -1; // No celebrity found
+    }
+};
+*/
+
+// time:O(2n) space:O(1)
+class Solution {
+public:
+    
+    int celebrity(vector<vector<int>>& mat) {
+        int n = mat.size();
+        int top = 0, bottom = n - 1;
+
+        // Narrow down the candidate
+        while (top < bottom) {
+            if (mat[top][bottom] == 1) {
+                top++;
+            } else {
+                bottom--;
+            }
+        }
+
+        // Verify the candidate
+        for (int i = 0; i < n; i++) {
+            if (i != top) { // Skip checking the diagonal
+                if (mat[top][i] == 1 || mat[i][top] == 0) {
+                    return -1;
+                }
+            }
+        }
+
+        return top; // The candidate is a celebrity
+    }
+};
+
+
+int main() {
+    Solution sol;
+    
+    // Example input matrix
+    vector<vector<int>> mat = {
+        {0, 1, 0},
+        {0, 0, 0},
+        {0, 1, 0}
+    };
+    
+    int result = sol.celebrity(mat);
+    
+    if (result != -1) {
+        cout << "Celebrity ID: " << result << endl;
+    } else {
+        cout << "No Celebrity Found" << endl;
+    }
+    
+    return 0;
+}