103. Binary Tree Zigzag Level Order Traversal

103. Binary Tree Zigzag Level Order Traversal

Author: SteffiKeranJ

zigzagLevelOrder.cpp

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
+        if(!root) return vector<vector<int>>();
+        queue<TreeNode*> q;
+        vector<vector<int>> res;
+        q.push(root);
+        bool ltr = true;
+        int i;
+        while(!q.empty()) {
+            int s = q.size();
+            vector<int> curLevel(s);
+            for(i=0; i < s; i++) {
+                TreeNode* cur = q.front();
+                q.pop();
+                int index = ltr ? i : s-1-i;
+                curLevel[index] = cur->val;
+                if(cur->left) q.push(cur->left);
+                if(cur->right) q.push(cur->right);
+                
+            }
+            if(!ltr) ltr = true;
+            else ltr = false;
+            res.push_back(curLevel);
+        }
+        return res;
+    }
+};