Add 20 more.

Author: iphkwan

Balanced_Binary_Tree.txt

@@ -0,0 +1,39 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    bool judge(TreeNode *root, int &depth) {
+        if (root == NULL) {
+            depth = 0;
+            return true;
+        }
+        int leftHeight, rightHeight;
+        if (judge(root->left, leftHeight) && judge(root->right, rightHeight)) {
+            if (leftHeight > rightHeight + 1 || rightHeight > leftHeight + 1)
+                return false;
+            if (leftHeight > rightHeight) {
+                depth = leftHeight + 1;
+            } else {
+                depth = rightHeight + 1;
+            }
+            return true;
+        }
+        return false;
+    }
+    bool isBalanced(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        if (root == NULL) {
+            return true;
+        }
+        int tmp = 0;
+        return judge(root, tmp);
+    }
+};

Binary_Tree_Inorder_Traversal.cc

@@ -0,0 +1,46 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<int> inorderTraversal(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        vector<int> ans;
+        if (root == NULL) {
+            return ans;
+        }
+        stack<TreeNode *> st;
+        stack<bool> flag;
+        st.push(root);
+        flag.push(false);
+        TreeNode *cntNode = NULL;
+        bool state;
+        while (!st.empty()) {
+            cntNode = st.top();
+            state = flag.top();
+            flag.pop();
+            if (state == false) {
+                flag.push(true);
+                if (cntNode->left) {
+                    st.push(cntNode->left);
+                    flag.push(false);
+                }
+            } else {
+                st.pop();
+                ans.push_back(cntNode->val);
+                if (cntNode->right) {
+                    st.push(cntNode->right);
+                    flag.push(false);
+                }
+            }
+        }
+        return ans;
+    }
+};

Binary_Tree_Level_Order_Traversal.cc

@@ -0,0 +1,51 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int> > levelOrder(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        vector<vector<int> > ans;
+        if (root == NULL) {
+            return ans;
+        }
+        vector<int> tmp;
+        queue<TreeNode *> q;
+        queue<int> dep_que;
+        q.push(root);
+        dep_que.push(1);
+        TreeNode *cntNode = NULL;
+        int cntDepth, minDepth = 1;
+        while (!q.empty()) {
+            cntNode = q.front();
+            q.pop();
+            cntDepth = dep_que.front();
+            dep_que.pop();
+            if (cntDepth > minDepth) {
+                minDepth = cntDepth;
+                ans.push_back(tmp);
+                tmp.clear();
+            }
+            tmp.push_back(cntNode->val);
+            if (cntNode->left) {
+                q.push(cntNode->left);
+                dep_que.push(cntDepth + 1);
+            }
+            if (cntNode->right) {
+                q.push(cntNode->right);
+                dep_que.push(cntDepth + 1);
+            }
+        }
+        if (tmp.size() > 0) {
+            ans.push_back(tmp);
+        }
+        return ans;
+    }
+};

Binary_Tree_Level_Order_Traversal_II.txt

@@ -0,0 +1,56 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int> > levelOrderBottom(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        stack<vector<int> > st;
+        vector<vector<int> > ans;
+        if (root == NULL) {
+            return ans;
+        }
+        vector<int> tmp;
+        queue<TreeNode *> q;
+        queue<int> dep_que;
+        TreeNode *cntNode;
+        int minDepth = 1, cntDepth;
+        q.push(root);
+        dep_que.push(1);
+        while (!q.empty()) {
+            cntNode = q.front();
+            q.pop();
+            cntDepth = dep_que.front();
+            dep_que.pop();
+            if (cntDepth > minDepth) {
+                st.push(tmp);
+                tmp.clear();
+                minDepth = cntDepth;
+            }
+            tmp.push_back(cntNode->val);
+            if (cntNode->left) {
+                q.push(cntNode->left);
+                dep_que.push(cntDepth + 1);
+            }
+            if (cntNode->right) {
+                q.push(cntNode->right);
+                dep_que.push(cntDepth + 1);
+            }
+        }
+        if (tmp.size() > 0) {
+            ans.push_back(tmp);
+        }
+        while (!st.empty()) {
+            ans.push_back(st.top());
+            st.pop();
+        }
+        return ans;
+    }
+};

Binary_Tree_Zigzag_Level_Order_Traversal.cc

@@ -0,0 +1,59 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int> > zigzagLevelOrder(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        vector<vector<int> > ans;
+        if (root == NULL) {
+            return ans;
+        }
+        queue<TreeNode *> q;
+        queue<int> dep_que;
+        vector<int> tmp;
+        q.push(root);
+        dep_que.push(1);
+        TreeNode *cntNode = NULL;
+        int cntDepth, minDepth = 1;
+        bool flag = false;
+        while (!q.empty()) {
+            cntNode = q.front();
+            q.pop();
+            cntDepth = dep_que.front();
+            dep_que.pop();
+            if (cntDepth > minDepth) {
+                minDepth = cntDepth;
+                if (flag) {
+                    reverse(tmp.begin(), tmp.end());
+                }
+                flag = !flag;
+                ans.push_back(tmp);
+                tmp.clear();
+            }
+            tmp.push_back(cntNode->val);
+            if (cntNode->left) {
+                q.push(cntNode->left);
+                dep_que.push(cntDepth + 1);
+            }
+            if (cntNode->right) {
+                q.push(cntNode->right);
+                dep_que.push(cntDepth + 1);
+            }
+        }
+        if (tmp.size() > 0) {
+            if (flag) {
+                reverse(tmp.begin(), tmp.end());
+            }
+            ans.push_back(tmp);
+        }
+        return ans;
+    }
+};

Construct_Binary_Tree_from_Inorder_and_Postorder_Traversal.cc

@@ -0,0 +1,34 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode *GenTree(vector<int> &inorder, int il, int ir, vector<int> &postorder, int pl, int pr) {
+        if (il > ir) {
+            return NULL;
+        }
+        TreeNode *root = new TreeNode(postorder[pr]);
+        int mid = il;
+        while (inorder[mid] != postorder[pr]) {
+            mid++;
+        }
+        int len = mid - il;
+        root->left = GenTree(inorder, il, mid - 1, postorder, pl, pl + len - 1);
+        root->right = GenTree(inorder, mid + 1, ir, postorder, pl + len, pr - 1);
+        return root;
+    }
+    TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        if (inorder.size() == 0) {
+            return NULL;
+        }
+        return GenTree(inorder, 0, inorder.size() - 1, postorder, 0, postorder.size() - 1);
+    }
+};

Construct_Binary_Tree_from_Preorder_and_Inorder_Traversal.cc

@@ -0,0 +1,34 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode *GenTree(vector<int> &preorder, int pl, int pr, vector<int> &inorder, int il, int ir) {
+        if (pl > pr) {
+            return NULL;
+        }
+        TreeNode *root = new TreeNode(preorder[pl]);
+        int mid = il;
+        while (inorder[mid] != preorder[pl]) {
+            mid++;
+        }
+        int len = mid - il;
+        root->left = GenTree(preorder, pl + 1, pl + len, inorder, il, mid - 1);
+        root->right = GenTree(preorder, pl + len + 1, pr, inorder, mid + 1, ir);
+        return root;
+    }
+    TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        if (preorder.size() == 0) {
+            return NULL;
+        }
+        return GenTree(preorder, 0, preorder.size() - 1, inorder, 0, inorder.size() - 1);
+    }
+};

Convert_Sorted_Array_to_Binary_Search_Tree.cc

@@ -0,0 +1,30 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode *GenTree(vector<int> &num, int l, int r) {
+        if (l > r) {
+            return NULL;
+        }
+        int mid = l + (r - l) / 2;
+        TreeNode *root = new TreeNode(num[mid]);
+        root->left = GenTree(num, l, mid - 1);
+        root->right = GenTree(num, mid + 1, r);
+        return root;
+    }
+    TreeNode *sortedArrayToBST(vector<int> &num) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        if (num.size() == 0) {
+            return NULL;
+        }
+        return GenTree(num, 0, num.size() - 1);
+    }
+};