Balanced BST

begeekmyfriend · begeekmyfriend · commit 5bb595bc2de0 · 2017-11-03T15:46:10.000+08:00
Signed-off-by: begeekmyfriend &lt;begeekmyfriend@gmail.com&gt;
diff --git a/110_balanced_binary_tree/Makefile b/110_balanced_binary_tree/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test balanced_bst.c
diff --git a/110_balanced_binary_tree/balanced_bst.c b/110_balanced_binary_tree/balanced_bst.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static int depth(struct TreeNode* root, bool *balance)
+{
+    if (!(*balance) || root == NULL) {
+        return 0;
+    }
+
+    int l = depth(root->left, balance) + 1;
+    int r = depth(root->right, balance) + 1;
+    if (*balance) {
+        int diff = l > r ? l - r : r - l;
+        *balance = diff < 2;
+    }
+    return l > r ? l : r;
+}
+
+static bool isBalanced(struct TreeNode* root)
+{
+    bool balance = true;
+    depth(root, &balance);
+    return balance;
+}
+
+int main(void)
+{
+    struct TreeNode root, n10, n11, n20, n21, n23, n30, n37;
+    root.val = 1;
+    n10.val = 2;
+    n11.val = 3;
+    n20.val = 4;
+    n21.val = 5;
+    n23.val = 6;
+    n30.val = 7;
+    n37.val = 8;
+    root.left = &n10;
+    root.right = &n11;
+    n10.left = &n20;
+    n10.right = &n21;
+    n11.left = NULL;
+    n11.right = &n23;
+    n20.left = &n30;
+    n20.right = NULL;
+    n21.left = NULL;
+    n21.right = NULL;
+    n23.left = NULL;
+    n23.right = &n37;
+    n30.left = NULL;
+    n30.right = NULL;
+    n37.left = NULL;
+    n37.right = NULL;
+
+    printf("%s\n", isBalanced(&root) ? "true" : "false");
+    return 0;
+}

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+all:`
	`2`	`+ gcc -O2 -o test balanced_bst.c`