Completed 1 exercise

Sample.java

@@ -0,0 +1,85 @@
+class Sample{
+    /***********PROBLEM-1***********/
+
+    /***********PROBLEM-2***********/
+    /* The knows API is defined in the parent class Relation.
+      boolean knows(int a, int b); */
+//TC:0(N*N)
+//SC:0(N)
+    public class Solution extends Relation {
+        public int findCelebrity(int n) {
+            int[] incoming=new int[n];
+            int[] outgoing=new int[n];
+            for(int i=0;i<n;i++){
+                for(int j=0;j<n;j++){
+                    if(knows(i,j)==true){
+                        outgoing[i]++;
+                        incoming[j]++;
+                    }
+
+                }
+            }
+            for(int i=0;i<n;i++){
+                if(incoming[i]==n && outgoing[i]==1){
+                    return i;
+                }
+            }
+            return -1;
+        }
+    }
+
+    /* The knows API is defined in the parent class Relation.
+          boolean knows(int a, int b); */
+//TC:0(N*N)
+//SC:0(N)
+    public class Solution extends Relation {
+        public int findCelebrity(int n) {
+            int[] indegree=new int[n];
+            for(int i=0;i<n;i++){
+                for(int j=0;j<n;j++){
+                    if(knows(i,j)==true){
+                        indegree[i]--;
+                        indegree[j]++;
+                    }
+
+                }
+            }
+            for(int i=0;i<n;i++){
+                if(indegree[i]==n-1){
+                    return i;
+                }
+            }
+            return -1;
+        }
+    }
+
+    /* The knows API is defined in the parent class Relation.
+      boolean knows(int a, int b); */
+//TC:0(N)
+//SC:0(N)
+    public class Solution extends Relation {
+        public int findCelebrity(int n) {
+            if(n==0){
+                return -1;
+            }
+            int celeb=0;
+            for(int i=0;i<n;i++){
+                if(i!=celeb){
+                    if(knows(celeb,i)){
+                        celeb=i;
+                    }
+                }
+            }
+            for(int i=0;i<n;i++){
+                if(i!=celeb){
+                    if(!knows(i,celeb) || knows(celeb,i)){
+                        return -1;
+                    }
+                }
+            }
+            return celeb;
+        }
+    }
+
+
+}