Accepted

Author: gouthampradhan

problems/src/PathSumIII.java

@@ -0,0 +1,51 @@
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Created by gouthamvidyapradhan on 08/04/2017.
+ * Accepted
+ */
+
+public class PathSumIII
+{
+    /**
+     *
+     */
+    public static class TreeNode
+    {
+        int val;
+        TreeNode left;
+        TreeNode right;
+        TreeNode(int x) { val = x; }
+    }
+
+    private Map<Integer, Integer> pathCount = new HashMap<>();
+    private int totalCount;
+
+    public static void main(String[] args) throws Exception
+    {
+        TreeNode node = new TreeNode(1);
+        System.out.println(new PathSumIII().pathSum(node, 0));
+    }
+
+    public int pathSum(TreeNode root, int sum)
+    {
+        if(root == null) return 0;
+        dfs(root, sum, 0);
+        return totalCount;
+    }
+
+    private void dfs(TreeNode root, int target, int pSum)
+    {
+        if(root != null)
+        {
+            pSum += root.val;
+            if(pSum == target) totalCount++;
+            totalCount += pathCount.getOrDefault(pSum - target, 0);
+            pathCount.put(pSum, pathCount.getOrDefault(pSum, 0) + 1);
+            dfs(root.left, target, pSum);
+            dfs(root.right, target, pSum);
+            pathCount.put(pSum, pathCount.get(pSum) - 1);
+        }
+    }
+}