--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/llrb/verifier/llrbContextWithVerifier.c	Tue Feb 02 16:12:34 2016 +0900
@@ -0,0 +1,45 @@
+#include "llrbContextWithVerifier.h"
+
+unsigned int min_height(struct Node* node, unsigned int height) {
+    if ((node->left == NULL) && (node->right == NULL)) return height;
+    if (node->left  == NULL) return min_height(node->right, height+1);
+    if (node->right == NULL) return min_height(node->left, height+1);
+
+    unsigned int left_min  = min_height(node->left, height+1);
+    unsigned int right_min = min_height(node->right, height+1);
+
+    if (left_min < right_min) {
+        return left_min;
+    } else {
+        return right_min;
+    }
+}
+
+unsigned int max_height(struct Node* node, unsigned int height) {
+    if ((node->left == NULL) && (node->right == NULL)) return height;
+    if (node->left  == NULL) return max_height(node->right, height+1);
+    if (node->right == NULL) return max_height(node->left, height+1);
+
+    unsigned int left_max  = max_height(node->left, height+1);
+    unsigned int right_max = max_height(node->right, height+1);
+
+    if (left_max > right_max) {
+        return left_max;
+    } else {
+        return right_max;
+    }
+}
+
+void verify_tree_height(struct Node* root) {
+    if (root == NULL) return;
+
+    unsigned int min_h = min_height(root, 1);
+    unsigned int max_h = max_height(root, 1);
+
+    if (max_h >= 2*min_h) {
+        printf("llrb-condition violated.\n");
+        printf("\tmin-height %u", min_h);
+        printf("\tmax-height %u", max_h);
+        exit(EXIT_FAILURE);
+    }
+}