Create Find if Path Exists in Graph.java

Author: sudoshivesh

easy/Find if Path Exists in Graph.java

@@ -0,0 +1,57 @@
+//1971. Find if Path Exists in Graph
+class DisjointSetUnion{
+    private int[] parent;
+    private int[] rank;
+    private int N;
+    
+    public DisjointSetUnion(int n){
+        this.N = n;
+        this.parent = new int[this.N];
+        this.rank = new int[this.N];
+        for(int i = 0; i < this.N; i++){
+            this.parent[i] = i;
+            this.rank[i] = 1;
+        }
+    }
+    
+    public boolean areConnected(int u, int v){
+        return find(u) == find(v);
+    }
+    
+    public void union(int u, int v){
+        if(u != v){
+            int a = find(u);
+            int b = find(v);
+            if(a != b){
+                if(rank[a] > rank[b]){
+                    parent[b] = a;
+                    rank[a] += rank[b];
+                }else{
+                    parent[a] = b;
+                    rank[b] += rank[a];
+                }
+            }
+        }
+    }
+    
+    private int find(int u){
+        int x = u;
+        while(x != this.parent[x]){
+            x = this.parent[x];
+        }
+        
+        this.parent[u] = x;
+        return x;
+    }
+}
+
+class Solution {
+    public boolean validPath(int n, int[][] edges, int start, int end) {
+        DisjointSetUnion set = new DisjointSetUnion(n);
+        for(int[] edge : edges){
+            set.union(edge[0], edge[1]);
+        }
+        
+        return set.areConnected(start, end);
+    }
+}