GH-169: Solve leetcode 101 (#182)

Author: rain1024

collections/leetcode/README.md

@@ -1,11 +1,13 @@
 # Leetcode
 
-Leetcode Solutions
+**Leetcode Solutions**
 
 * 🟢 Easy
 * 🟡 Medium
 * 🔴 Hard 
 
+**Problems**
+
 <table>
 <tr><td>🟢&nbsp;<a href='https://github.com/rain1024/datastructures-algorithms-competitive-programming/tree/main/problems/leetcode1'>1</a></td>
 <td>2</td>
@@ -117,7 +119,7 @@ Leetcode Solutions
 <td>99</td>
 <td>100</td>
 <tr>
-<td>101</td>
+<td>🟢&nbsp;<a href='https://github.com/rain1024/datastructures-algorithms-competitive-programming/tree/main/problems/leetcode101'>101</a></td>
 <td>102</td>
 <td>103</td>
 <td>104</td>

collections/leetcode/data.yaml

@@ -14,6 +14,9 @@ problems:
 - name: 78
   languages: cpp
   level: medium
+- name: 101
+  languages: cpp
+  level: easy
 - name: 142
   languages: cpp
   level: medium

problems/leetcode101/.gitignore

@@ -0,0 +1,2 @@
+solution
+*.dSYM

problems/leetcode101/README.md

@@ -0,0 +1,19 @@
+# Leetcode Problem 
+
+## Usage
+
+Run program with an example
+
+```
+bazel run cpp/main:solution < data/1.in
+```
+
+Test program
+
+```
+# Run all tests
+bazel test --test_output=all tests:solution_test
+bazel test --test_output=all --cache_test_results=no tests:solution_test
+# Run test with pecific test id
+bazel test --test_output=all tests:solution_test --test_arg=1
+```

tools/craft/templates/leetcode/src/main/BUILD renamed to problems/leetcode101/cpp/main/BUILD

@@ -0,0 +1,86 @@
+#include "solution.h"
+
+#include <algorithm>
+#include <cmath>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+TreeNode* parse_tree(string s) {
+  // parse tree from string with format
+  // 1 2 3 4 5 6 null 7
+  string value = "";
+  vector<TreeNode*> nodes;
+  TreeNode* node;
+  for (int i = 0; i < s.size(); i++) {
+    if (s[i] == ' ') {
+      if (value == "null") {
+        node = nullptr;
+      } else {
+        node = new TreeNode(stoi(value));
+      }
+      value = "";
+      nodes.push_back(node);
+    } else {
+      value += s[i];
+    }
+  }
+  if (value == "null") {
+    node = nullptr;
+  } else {
+    node = new TreeNode(stoi(value));
+  }
+  nodes.push_back(node);
+  int n = nodes.size();
+  queue<TreeNode*> q;
+  TreeNode* head = nodes[0];
+  q.push(head);
+  int i = 1;
+  while (!q.empty() && i < n) {
+    node = q.front();
+    q.pop();
+    node->left = nodes[i];
+    node->right = nodes[i + 1];
+    q.push(nodes[i]);
+    q.push(nodes[i + 1]);
+    i += 2;
+  }
+  return head;
+}
+
+int main() {
+  ios::sync_with_stdio(false);
+  cin.tie(0);
+
+  bool is_use_file = false;
+
+  filesystem::path filepath =
+      filesystem::current_path().parent_path().parent_path() / "data" / "1.in";
+  ifstream file(filepath);
+
+  if (is_use_file) {
+    cin.rdbuf(file.rdbuf());  // redirect cin to file
+  }
+
+  // get input
+  string s;
+  getline(cin, s);
+
+  cout << "s = " << s << endl;
+
+  TreeNode* root = parse_tree(s);
+
+  // TreeNode* root = new TreeNode(0);
+
+  Solution solution;
+  bool output = solution.isSymmetric(root);
+
+  // print output
+  cout << output << endl;
+
+  return 0;
+}

problems/leetcode101/cpp/main/solution.cpp

@@ -0,0 +1,72 @@
+#include <algorithm>
+#include <cmath>
+#include <map>
+#include <queue>
+#include <set>
+#include <stack>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+using namespace std;
+
+struct TreeNode {
+  int val;
+  TreeNode *left;
+  TreeNode *right;
+  TreeNode() : val(0), left(nullptr), right(nullptr) {}
+  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+  TreeNode(int x, TreeNode *left, TreeNode *right)
+      : val(x), left(left), right(right) {}
+};
+
+class Solution {
+ public:
+  bool isEquals(vector<TreeNode *> lefts, vector<TreeNode *> rights) {
+    if (lefts.size() != rights.size()) {
+      return false;
+    }
+    int n = lefts.size();
+    TreeNode *left, *right;
+    for (int i = 0; i < lefts.size(); i++) {
+      left = lefts[i];
+      right = rights[n - 1 - i];
+      if (left == nullptr && right == nullptr) {
+        continue;
+      } else if (left != nullptr && right != nullptr) {
+        if (left->val != right->val) {
+          return false;
+        }
+      } else {
+        return false;
+      }
+    }
+    vector<TreeNode *> left_nexts, right_nexts;
+    int num_not_nulls = 0;
+    for (int i = 0; i < lefts.size(); i++) {
+      left = lefts[i];
+      right = rights[i];
+      if (left != nullptr) {
+        num_not_nulls += 1;
+        left_nexts.push_back(left->left);
+        left_nexts.push_back(left->right);
+      }
+      if (right != nullptr) {
+        right_nexts.push_back(right->left);
+        right_nexts.push_back(right->right);
+      }
+    }
+    if (num_not_nulls > 0) {
+      return isEquals(left_nexts, right_nexts);
+    } else {
+      return true;
+    }
+  }
+
+  bool isSymmetric(TreeNode *root) {
+    if (!root) {
+      return true;
+    }
+    return isEquals({root->left}, {root->right});
+  }
+};

problems/leetcode101/cpp/main/solution.h

@@ -0,0 +1 @@
+1 2 2 3 4 4 3