"Populating Next Right Pointers in Each Node"

Author: lennylxx

README.md

@@ -172,7 +172,7 @@ The `☢` means that you need to have a LeetCode Premium Subscription.
 | 119 | [Pascal's Triangle II]                                       | [C](src/119.c)     |
 | 118 | [Pascal's Triangle]                                          | [C](src/118.c)     |
 | 117 | [Populating Next Right Pointers in Each Node II]             |                    |
-| 116 | [Populating Next Right Pointers in Each Node]                |                    |
+| 116 | [Populating Next Right Pointers in Each Node]                | [C](src/116.c)     |
 | 115 | [Distinct Subsequences]                                      |                    |
 | 114 | [Flatten Binary Tree to Linked List]                         |                    |
 | 113 | [Path Sum II]                                                |                    |

src/116.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct TreeLinkNode {
+    int val;
+    struct TreeLinkNode *left, *right, *next;
+};
+
+void connectHelper(struct TreeLinkNode *node, struct TreeLinkNode *sibling) {
+    if (node == NULL) return;
+    if (!node->left || !node->right) return;
+
+    /* node have two children */
+    node->left->next = node->right;
+    node->right->next = (sibling == NULL) ? NULL : sibling->left;
+
+    connectHelper(node->left, node->right);
+    connectHelper(node->right, node->right->next);
+}
+
+void connect(struct TreeLinkNode *root) {
+    if (root == NULL) return;
+
+    root->next = NULL;
+    connectHelper(root, NULL);
+}
+
+int main() {
+    struct TreeLinkNode *root = (struct TreeLinkNode *)calloc(7, sizeof(struct TreeLinkNode));
+    root->val = 1;
+    root->left = root + 1;
+    root->left->val = 2;
+    root->right = root + 2;
+    root->right->val = 3;
+
+    root->left->left = root + 3;
+    root->left->left->val = 4;
+    root->left->right = root + 4;
+    root->left->right->val = 5;
+
+    root->right->left = root + 5;
+    root->right->left->val = 6;
+    root->right->right = root + 6;
+    root->right->right->val = 7;
+
+    connect(root);
+
+    return 0;
+}