通过一个排序了的数组构建一个二叉查找树!
这个题使用反向的二叉查找解决:
[1 2 3 4 5]
这个题的思想是很简单的,通过一个简单的例子加上伪代码来表示这样的一个变化情况:
low = 0 , high = 4 -> mid = 2
TreeNode node = new TreeNode(mid);
node.left = recursiveHelper(nums,low ,mid -1);
node.right = recursiveHelper(nums,mid + 1, high);
public TreeNode sortedArrayToBST(int[] num) {
if (num.length == 0) {
return null;
}
TreeNode head = helper(num, 0, num.length - 1);
return head;
}
public TreeNode helper(int[] num, int low, int high) {
if (low > high) { // Done
return null;
}
int mid = (low + high) / 2;
TreeNode node = new TreeNode(num[mid]);
node.left = helper(num, low, mid - 1);
node.right = helper(num, mid + 1, high);
return node;
}
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