Create 117.cpp

LeetCode/117.cpp

@@ -0,0 +1,51 @@
+
+class Solution {
+public:
+    Node* processLevel(Node* leftMost) {
+        Node* nextLevelLeftMost = nullptr;
+        Node* nextLevelNext = nullptr;
+        for (Node* current = leftMost; current != nullptr; current = current->next) {
+            if (current->left && current->right) {
+                current->left->next = current->right;
+                if (!nextLevelLeftMost) {
+                    nextLevelLeftMost = current->left;
+                    nextLevelNext = current->right;
+                }
+                else {
+                    nextLevelNext->next = current->left;
+                    nextLevelNext = current->right;
+                }
+            }
+            else if (current->left) {
+                if (!nextLevelLeftMost) {
+                    nextLevelLeftMost = current->left;
+                    nextLevelNext = current->left;
+                }
+                else {
+                    nextLevelNext->next = current->left;
+                    nextLevelNext = current->left;
+                }
+            }
+            else if (current->right) {
+                if (!nextLevelLeftMost) {
+                    nextLevelLeftMost = current->right;
+                    nextLevelNext = current->right;
+                }
+                else {
+                    nextLevelNext->next = current->right;
+                    nextLevelNext = current->right;
+                }
+            }
+        }
+
+        return nextLevelLeftMost;
+    }
+
+    Node* connect(Node* root) {
+        Node* nextLevelEntry = root;
+        while (nextLevelEntry) {
+            nextLevelEntry = processLevel(nextLevelEntry);
+        }
+        return root;
+    }
+};