update binary tree (#89)

* update binary tree

* test if binary trees is same

Author: realDuYuanChao

datastructures/binarytree/count_left_nodes_of_binary_tree.c renamed to datastructures/binarytree/count_leaf_nodes_of_binary_tree.c

@@ -28,11 +28,11 @@ Node *createNode(int data) {
 int countLeafNodes(Node *root) {
     if (root == NULL) {
         return 0;
-    } else if (root->left == NULL && root->right == NULL) {
+    }
+    if (root->left == NULL && root->right == NULL) {
         return 1;
-    } else {
-        return countLeafNodes(root->left) + countLeafNodes(root->right);
     }
+    return countLeafNodes(root->left) + countLeafNodes(root->right);
 }
 
 void test() {

datastructures/binarytree/is_same_binary_tree.c

@@ -30,15 +30,14 @@ Node *createNode(int data) {
 bool isSame(Node *root1, Node *root2) {
     if (root1 == NULL && root2 == NULL) {
         return true;
-    } else if (root1 != NULL && root2 != NULL) {
-        if (root1->data == root2->data) {
-            return isSame(root1->left, root2->left) && isSame(root1->right, root2->right);
-        } else {
-            return false;
-        }
-    } else {
+    }
+    if (root1 == NULL || root2 == NULL) {
+        return false;
+    }
+    if (root1->data != root2->data) {
         return false;
     }
+    return isSame(root1->left, root2->left) && isSame(root1->right, root2->right);
 }
 
 
@@ -61,6 +60,7 @@ void test() {
     node5->left = node5->right = NULL;
 
     assert(isSame(root, root));
+    assert(!isSame(root, NULL));
 }
 
 int main() {