Done Graph-3

Solution.java

@@ -0,0 +1,29 @@
+//TC: O(n): one pass to select a candidate (n−1 checks) + one pass to verify (O(n) checks).
+//SC: O(1): constant extra variables.
+
+//Pick candidate by scanning i=1..n−1; if candidate knows i, set candidate=i (others can’t be celeb).
+//Verify candidate: for every i≠candidate, ensure candidate doesn’t know i and i knows candidate.
+//If any verification fails return -1; otherwise return the candidate.
+
+public class Solution extends Relation {
+    public int findCelebrity(int n) {
+        int ptnlCand = 0;
+
+        for(int i = 1; i < n; i++){
+            if(knows(ptnlCand, i)){
+                ptnlCand = i;
+            }
+        }
+
+        for(int i = 0; i < n; i++){
+            if(i == ptnlCand) continue;
+            if(i < ptnlCand){
+                if(knows(ptnlCand, i) || !knows(i, ptnlCand)) return -1;
+            } else {
+                if(!knows(i, ptnlCand)) return -1;
+            }
+        }
+
+        return ptnlCand;
+    }
+}