Convertion between bst and linked list

Signed-off-by: Leo Ma <[email protected]>

109_convert_sorted_list_to_binary_search_tree/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test bst_convert.c

109_convert_sorted_list_to_binary_search_tree/bst_convert.c

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct ListNode {
+    int val;
+    struct ListNode *next;
+};
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static struct TreeNode *recursive(int *nums, int lo, int hi)
+{
+    int mid = lo + (hi - lo) / 2;
+    struct TreeNode *node = malloc(sizeof(*node));
+    node->val = nums[mid];
+    node->left = mid > lo ? recursive(nums, lo, mid - 1) : NULL;
+    node->right = mid < hi ? recursive(nums, mid + 1, hi) : NULL;
+    return node;
+}
+
+static struct TreeNode *sortedListToBST(struct ListNode *head)
+{
+    int i, nums[10000];
+    for (i = 0; head != NULL; head = head->next, i++) {
+        nums[i] = head->val;
+    }
+    if (i == 0) {
+        return NULL;
+    }
+    return recursive(nums, 0, i - 1);
+}
+
+int main(int argc, char **argv)
+{
+    sortedListToBST(NULL);
+    return 0;
+}

114_flatten_binary_tree_to_linked_list/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test flatten.c

114_flatten_binary_tree_to_linked_list/flatten.c

@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static struct TreeNode *recursive(struct TreeNode *node)
+{
+    if (node == NULL) {
+        return NULL;
+    }
+
+    if (node->right == NULL && node->left == NULL) {
+        return node;
+    }
+
+    struct TreeNode *right_last = recursive(node->right);
+    struct TreeNode *left_last = recursive(node->left);
+
+    if (left_last != NULL) {
+        left_last->right = node->right;
+        node->right = node->left;
+        node->left = NULL;
+    }
+
+    return right_last != NULL ? right_last : left_last;
+}
+
+static void flatten(struct TreeNode *root)
+{
+    recursive(root);
+}
+
+int main(void)
+{
+    struct TreeNode root, n1[2], n2[4], n3[8];
+    root.val = 5;
+    n1[0].val = 4;
+    n1[1].val = 8;
+    n2[0].val = 11;
+    n2[2].val = 13;
+    n2[3].val = 4;
+    n3[0].val = 7;
+    n3[1].val = 2;
+    n3[6].val = 5;
+    n3[7].val = 1;
+
+    root.left = &n1[0];
+    root.right = &n1[1];
+    n1[0].left = &n2[0];
+    n1[0].right = NULL;
+    n1[1].left = &n2[2];
+    n1[1].right = &n2[3];
+    n2[0].left = &n3[0];
+    n2[0].right = &n3[1];
+    n2[2].left = NULL;
+    n2[2].right = NULL;
+    n2[3].left = &n3[6];
+    n2[3].right = &n3[7];
+    n3[0].left = NULL;
+    n3[0].right = NULL;
+    n3[1].left = NULL;
+    n3[1].right = NULL;
+    n3[6].left = NULL;
+    n3[6].right = NULL;
+    n3[7].left = NULL;
+    n3[7].right = NULL;
+
+    flatten(&root);
+
+    struct TreeNode *p;
+    for (p = &root; p != NULL; p = p->right) {
+        printf("%d ", p->val);
+    }
+    printf("\n");
+    return 0;
+}