写了个tostring

homework4/BiTree.cpp

@@ -1,38 +1,39 @@
 #include "BiTree.h"
+#include <sstream>
 
 bool BiTree::is_empty(BiTree *bt) {
-    if(bt==nullptr) {
+    if (bt == nullptr) {
         return true;
     }
     return false;
 }
 
 bool BiTree::is_leaf(BiTree *bt) {
-    if(bt->left==nullptr && bt->right==nullptr) {
+    if (bt->left == nullptr && bt->right == nullptr) {
         return true;
     }
     return false;
 }
 
 int BiTree::sum_leaf(BiTree *bt) {
-    if(is_empty(bt)) {
+    if (is_empty(bt)) {
         return 0;
     }
-    if(is_leaf(bt)) {
+    if (is_leaf(bt)) {
         return bt->data;
     }
-    return sum_leaf(bt->left)+sum_leaf(bt->right);
+    return sum_leaf(bt->left) + sum_leaf(bt->right);
 }
 
-BiTree* BiTree::createNode(int data) {
-    BiTree* newNode = new BiTree();
+BiTree *BiTree::createNode(int data) {
+    BiTree *newNode = new BiTree();
     newNode->data = data;
     newNode->left = nullptr;
     newNode->right = nullptr;
     return newNode;
 }
 
-void BiTree::insertNode(BiTree*& bt, int value) {
+void BiTree::insertNode(BiTree *&bt, int value) {
     if (bt == nullptr) {
         bt = createNode(value);
     } else {
@@ -42,4 +43,23 @@ void BiTree::insertNode(BiTree*& bt, int value) {
             insertNode(bt->right, value);
         }
     }
-}
+}
+
+
+void toStringHelper(const BiTree *node, std::ostringstream &oss, const std::string &prefix, bool isLeft) {
+    if (node != nullptr) {
+        oss << prefix;
+
+        oss << (isLeft ? "|--" : "|--") << node->data << "\n";
+
+        std::string newPrefix = prefix + (isLeft ? "|   " : "    ");
+        toStringHelper(node->left, oss, newPrefix, true);
+        toStringHelper(node->right, oss, newPrefix, false);
+    }
+}
+
+std::string BiTree::toString() {
+    std::ostringstream oss;
+    toStringHelper(this, oss, "", false);
+    return oss.str();
+}