Added solution to find paths with target sum

YogenRaii · YogenRaii · commit 3fc3a3c7abab · 2019-06-06T21:48:58.000-05:00
diff --git a/src/main/java/com/eprogrammerz/examples/algorithm/trees/Node.java b/src/main/java/com/eprogrammerz/examples/algorithm/trees/Node.java
@@ -2,6 +2,7 @@
 
 import java.util.LinkedList;
 import java.util.Queue;
+import java.util.Stack;
 
 public class Node {
     int data;
@@ -105,6 +106,42 @@ private boolean isSubtree(Node t1, Node t2) {
         return isSubtree(t1.left, t2.left) && isSubtree(t1.right, t2.right);
     }
 
+    /**
+     * Count path that sums to the target value
+     *
+     * @return
+     */
+    public int findPaths(int target) {
+        Queue<Node> queue = new LinkedList<>();
+        queue.add(this);
+
+        int count = 0;
+        while (!queue.isEmpty()) {
+            Node node = queue.poll();
+
+            count += findPaths(node, target, 0);
+
+            if (node.left != null) queue.add(node.left);
+
+            if (node.right != null) queue.add(node.right);
+        }
+        return count;
+    }
+
+    private int findPaths(Node node, int target, int sum) {
+        if (node == null) return 0;
+        sum += node.data;
+
+        int totalPaths = 0;
+        if (target == sum) {
+            totalPaths++;
+        }
+        totalPaths += findPaths(node.left, target, sum);
+        totalPaths += findPaths(node.right, target, sum);
+
+        return totalPaths;
+    }
+
     @Override
     public String toString() {
         return "(" + data + ")";
diff --git a/src/main/java/com/eprogrammerz/examples/algorithm/trees/PathWithSum.java b/src/main/java/com/eprogrammerz/examples/algorithm/trees/PathWithSum.java
@@ -0,0 +1,31 @@
+package com.eprogrammerz.examples.algorithm.trees;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class PathWithSum {
+    @Test
+    public void testFindPath() {
+        /**
+         *          10
+         *       /     \
+         *     7         2
+         *   /   \        \
+         *  3     4        8
+         *                  \
+         *                   12
+         *
+         */
+
+        Node root = new Node(10);
+        root.left = new Node(7);
+        root.right = new Node(2);
+        root.left.left = new Node(3);
+        root.left.right = new Node(4);
+        root.right.right = new Node(8);
+        root.right.right.right = new Node(12);
+
+        assertEquals(3, root.findPaths(20));
+    }
+}
