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codes/cpp/include/PrintUtil.hpp

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+/*
+ * File: PrintUtil.hpp
+ * Created Time: 2021-12-19
+ * Author: Krahets (krahets@163.com)
+ */
+
+#pragma once
+
+#include <iostream>
+#include <string>
+#include <sstream>
+#include "ListNode.hpp"
+#include "TreeNode.hpp"
+
+class PrintUtil {
+    public:
+        /**
+         * @brief Find an element in a vector
+         * 
+         * @tparam T 
+         * @param vec 
+         * @param ele 
+         * @return int 
+         */
+        template <typename T>
+        static int vecFind(const vector<T>& vec, T ele) {
+            int j = INT_MAX;
+            for (int i = 0; i < vec.size(); i++) {
+                if (vec[i] == ele) {
+                    j = i;
+                }
+            }
+            return j;
+        }
+
+        /**
+         * @brief Concatenate a vector with a delim
+         * 
+         * @tparam T 
+         * @param delim 
+         * @param vec 
+         * @return string 
+         */
+        template <typename T>
+        static string strJoin(const string& delim, const T& vec) {
+            ostringstream s;
+            for (const auto& i : vec) {
+                if (&i != &vec[0]) {
+                    s << delim;
+                }
+                s << i;
+            }
+            return s.str();
+        }
+
+        /**
+         * @brief Repeat a string for n times
+         * 
+         * @param str 
+         * @param n 
+         * @return string 
+         */
+        static string strRepeat(string str, int n) {
+            ostringstream os;
+            for(int i = 0; i < n; i++)
+                os << str;
+            return os.str();
+        }
+
+        /**
+         * @brief Get the Vector String object
+         * 
+         * @tparam T 
+         * @param list 
+         * @return string 
+         */
+        template <typename T>
+        static string getVectorString(vector<T> &list) {
+            return "[" + strJoin(", ", list) + "]";
+        }
+
+        /**
+         * @brief Print a vector
+         * 
+         * @tparam T 
+         * @param list 
+         */
+        template <typename T>
+        static void printVector(vector<T> &list) {
+            cout << getVectorString(list) << '\n';
+        }
+
+        /**
+         * @brief Print a vector matrix
+         * 
+         * @tparam T 
+         * @param matrix 
+         */
+        template <typename T>
+        static void printVectorMatrix(vector<vector<T>> &matrix) {
+            cout << "[" << '\n';
+            for (vector<T> &list : matrix)
+                cout << "  " + getVectorString(list) + "," << '\n';
+            cout << "]" << '\n';
+        }
+
+        /**
+         * @brief Print a linked list
+         * 
+         * @param head 
+         */
+        static void printLinkedList(ListNode *head) {
+            vector<int> list;
+            while (head != nullptr) {
+                list.push_back(head->val);
+                head = head->next;
+            }
+            
+            cout << strJoin(" -> ", list) << '\n';
+        }
+
+        /**
+         * @brief This tree printer is borrowed from TECHIE DELIGHT
+         *        https://www.techiedelight.com/c-program-print-binary-tree/
+         */
+        struct Trunk {
+            Trunk *prev;
+            string str;
+            Trunk(Trunk *prev, string str) {
+                this->prev = prev;
+                this->str = str;
+            }
+        };
+        
+        /**
+         * @brief Helper function to print branches of the binary tree
+         * 
+         * @param p 
+         */
+        static void showTrunks(Trunk *p) {
+            if (p == nullptr) {
+                return;
+            }
+        
+            showTrunks(p->prev);
+            cout << p->str;
+        }
+
+        /**
+         * @brief The interface of the tree printer
+         * 
+         * @param root 
+         */
+        static void printTree(TreeNode *root) {
+            printTree(root, nullptr, false);
+        }
+
+        /**
+         * @brief Print a binary tree
+         * 
+         * @param root 
+         * @param prev 
+         * @param isLeft 
+         */
+        static void printTree(TreeNode *root, Trunk *prev, bool isLeft) {
+            if (root == nullptr) {
+                return;
+            }
+        
+            string prev_str = "    ";
+            Trunk *trunk = new Trunk(prev, prev_str);
+        
+            printTree(root->right, trunk, true);
+        
+            if (!prev) {
+                trunk->str = "———";
+            }
+            else if (isLeft) {
+                trunk->str = "/———";
+                prev_str = "   |";
+            }
+            else {
+                trunk->str = "\\———";
+                prev->str = prev_str;
+            }
+        
+            showTrunks(trunk);
+            cout << " " << root->val << endl;
+        
+            if (prev) {
+                prev->str = prev_str;
+            }
+            trunk->str = "   |";
+        
+            printTree(root->left, trunk, false);
+        }
+};