Add 47_Number_of_Provinces.java

Author: seanprashad

Graphs/47_Number_of_Provinces.java

@@ -0,0 +1,67 @@
+class Solution {
+    public int findCircleNum(int[][] isConnected) {
+        if (isConnected == null || isConnected.length == 0) {
+            return 0;
+        }
+
+        UnionFind uf = new UnionFind(isConnected.length);
+
+        for (int i = 0; i < isConnected.length; i++) {
+            for (int j = 0; j < isConnected[i].length; j++) {
+                if (isConnected[i][j] == 1) {
+                    uf.union(i, j);
+                }
+            }
+        }
+
+        return uf.count();
+    }
+
+    private class UnionFind {
+        private int[] parents, size;
+        private int count;
+
+        public UnionFind(int n) {
+            parents = new int[n];
+            size = new int[n];
+            count = n;
+
+            for (int i = 0; i < parents.length; i++) {
+                parents[i] = i;
+                size[i] = 1;
+            }
+        }
+
+        public int find(int node) {
+            if (parents[node] == node) {
+                return node;
+            }
+
+            parents[node] = find(parents[parents[node]]);
+            return parents[node];
+        }
+
+        public void union(int x, int y) {
+            int xParent = find(x);
+            int yParent = find(y);
+
+            if (xParent == yParent) {
+                return;
+            }
+
+            if (size[xParent] > size[yParent]) {
+                parents[yParent] = xParent;
+                size[xParent] += size[yParent];
+            } else {
+                parents[xParent] = yParent;
+                size[yParent] += size[xParent];
+            }
+
+            --count;
+        }
+
+        public int count() {
+            return count;
+        }
+    }
+}