package chapter_3_binarytreeproblem;
import java.util.Stack;
public class Problem_10_RecoverBST {
public static class Node {
public int value;
public Node left;
public Node right;
public Node(int data) {
this.value = data;
}
}
public static Node[] getTwoErrNodes(Node head) {
Node[] errs = new Node[2];
if (head == null) {
return errs;
}
Stack<Node> stack = new Stack<Node>();
Node pre = null;
while (!stack.isEmpty() || head != null) {
if (head != null) {
stack.push(head);
head = head.left;
} else {
head = stack.pop();
if (pre != null && pre.value > head.value) {
errs[0] = errs[0] == null ? pre : errs[0];
errs[1] = head;
}
pre = head;
head = head.right;
}
}
return errs;
}
public static Node[] getTwoErrParents(Node head, Node e1, Node e2) {
Node[] parents = new Node[2];
if (head == null) {
return parents;
}
Stack<Node> stack = new Stack<Node>();
while (!stack.isEmpty() || head != null) {
if (head != null) {
stack.push(head);
head = head.left;
} else {
head = stack.pop();
if (head.left == e1 || head.right == e1) {
parents[0] = head;
}
if (head.left == e2 || head.right == e2) {
parents[1] = head;
}
head = head.right;
}
}
return parents;
}
public static Node recoverTree(Node head) {
Node[] errs = getTwoErrNodes(head);
Node[] parents = getTwoErrParents(head, errs[0], errs[1]);
Node e1 = errs[0];
Node e1P = parents[0];
Node e1L = e1.left;
Node e1R = e1.right;
Node e2 = errs[1];
Node e2P = parents[1];
Node e2L = e2.left;
Node e2R = e2.right;
if (e1 == head) {
if (e1 == e2P) { // 情况一
e1.left = e2L;
e1.right = e2R;
e2.right = e1;
e2.left = e1L;
} else if (e2P.left == e2) { // 情况二
e2P.left = e1;
e2.left = e1L;
e2.right = e1R;
e1.left = e2L;
e1.right = e2R;
} else { // 情况三
e2P.right = e1;
e2.left = e1L;
e2.right = e1R;
e1.left = e2L;
e1.right = e2R;
}
head = e2;
} else if (e2 == head) {
if (e2 == e1P) { // 情况四
e2.left = e1L;
e2.right = e1R;
e1.left = e2;
e1.right = e2R;
} else if (e1P.left == e1) { // 情况五
e1P.left = e2;
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
} else { // 情况六
e1P.right = e2;
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
}
head = e1;
} else {
if (e1 == e2P) {
if (e1P.left == e1) { // 情况七
e1P.left = e2;
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1;
} else { // 情况八
e1P.right = e2;
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1;
}
} else if (e2 == e1P) {
if (e2P.left == e2) { // 情况九
e2P.left = e1;
e2.left = e1L;
e2.right = e1R;
e1.left = e2;
e1.right = e2R;
} else { // 情况十
e2P.right = e1;
e2.left = e1L;
e2.right = e1R;
e1.left = e2;
e1.right = e2R;
}
} else {
if (e1P.left == e1) {
if (e2P.left == e2) { // 情况十一
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
e1P.left = e2;
e2P.left = e1;
} else { // 情况十二
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
e1P.left = e2;
e2P.right = e1;
}
} else {
if (e2P.left == e2) { // 情况十三
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
e1P.right = e2;
e2P.left = e1;
} else { // 情况十四
e1.left = e2L;
e1.right = e2R;
e2.left = e1L;
e2.right = e1R;
e1P.right = e2;
e2P.right = e1;
}
}
}
}
return head;
}
// for test -- print tree
public static void printTree(Node head) {
System.out.println("Binary Tree:");
printInOrder(head, 0, "H", 17);
System.out.println();
}
public static void printInOrder(Node head, int height, String to, int len) {
if (head == null) {
return;
}
printInOrder(head.right, height + 1, "v", len);
String val = to + head.value + to;
int lenM = val.length();
int lenL = (len - lenM) / 2;
int lenR = len - lenM - lenL;
val = getSpace(lenL) + val + getSpace(lenR);
System.out.println(getSpace(height * len) + val);
printInOrder(head.left, height + 1, "^", len);
}
public static String getSpace(int num) {
String space = " ";
StringBuffer buf = new StringBuffer("");
for (int i = 0; i < num; i++) {
buf.append(space);
}
return buf.toString();
}
// for test
public static boolean isBST(Node head) {
if (head == null) {
return false;
}
Stack<Node> stack = new Stack<Node>();
Node pre = null;
while (!stack.isEmpty() || head != null) {
if (head != null) {
stack.push(head);
head = head.left;
} else {
head = stack.pop();
if (pre != null && pre.value > head.value) {
return false;
}
pre = head;
head = head.right;
}
}
return true;
}
public static void main(String[] args) {
Node head = new Node(5);
head.left = new Node(3);
head.right = new Node(7);
head.left.left = new Node(2);
head.left.right = new Node(4);
head.right.left = new Node(6);
head.right.right = new Node(8);
head.left.left.left = new Node(1);
printTree(head);
System.out.println(isBST(head));
// 情况1, 7 -> e1, 5 -> e2
System.out.println("situation 1");
Node head1 = new Node(7);
head1.left = new Node(3);
head1.right = new Node(5);
head1.left.left = new Node(2);
head1.left.right = new Node(4);
head1.right.left = new Node(6);
head1.right.right = new Node(8);
head1.left.left.left = new Node(1);
printTree(head1);
System.out.println(isBST(head1));
Node res1 = recoverTree(head1);
printTree(res1);
System.out.println(isBST(res1));
// 情况2, 6 -> e1, 5 -> e2
System.out.println("situation 2");
Node head2 = new Node(6);
head2.left = new Node(3);
head2.right = new Node(7);
head2.left.left = new Node(2);
head2.left.right = new Node(4);
head2.right.left = new Node(5);
head2.right.right = new Node(8);
head2.left.left.left = new Node(1);
printTree(head2);
System.out.println(isBST(head2));
Node res2 = recoverTree(head2);
printTree(res2);
System.out.println(isBST(res2));
// 情况3, 8 -> e1, 5 -> e2
System.out.println("situation 3");
Node head3 = new Node(8);
head3.left = new Node(3);
head3.right = new Node(7);
head3.left.left = new Node(2);
head3.left.right = new Node(4);
head3.right.left = new Node(6);
head3.right.right = new Node(5);
head3.left.left.left = new Node(1);
printTree(head3);
System.out.println(isBST(head3));
Node res3 = recoverTree(head3);
printTree(res3);
System.out.println(isBST(res3));
// 情况4, 5 -> e1, 3 -> e2
System.out.println("situation 4");
Node head4 = new Node(3);
head4.left = new Node(5);
head4.right = new Node(7);
head4.left.left = new Node(2);
head4.left.right = new Node(4);
head4.right.left = new Node(6);
head4.right.right = new Node(8);
head4.left.left.left = new Node(1);
printTree(head4);
System.out.println(isBST(head4));
Node res4 = recoverTree(head4);
printTree(res4);
System.out.println(isBST(res4));
// 情况5, 5 -> e1, 2 -> e2
System.out.println("situation 5");
Node head5 = new Node(2);
head5.left = new Node(3);
head5.right = new Node(7);
head5.left.left = new Node(5);
head5.left.right = new Node(4);
head5.right.left = new Node(6);
head5.right.right = new Node(8);
head5.left.left.left = new Node(1);
printTree(head5);
System.out.println(isBST(head5));
Node res5 = recoverTree(head5);
printTree(res5);
System.out.println(isBST(res5));
// 情况6, 5 -> e1, 4 -> e2
System.out.println("situation 6");
Node head6 = new Node(4);
head6.left = new Node(3);
head6.right = new Node(7);
head6.left.left = new Node(2);
head6.left.right = new Node(5);
head6.right.left = new Node(6);
head6.right.right = new Node(8);
head6.left.left.left = new Node(1);
printTree(head6);
System.out.println(isBST(head6));
Node res6 = recoverTree(head6);
printTree(res6);
System.out.println(isBST(res6));
// 情况7, 4 -> e1, 3 -> e2
System.out.println("situation 7");
Node head7 = new Node(5);
head7.left = new Node(4);
head7.right = new Node(7);
head7.left.left = new Node(2);
head7.left.right = new Node(3);
head7.right.left = new Node(6);
head7.right.right = new Node(8);
head7.left.left.left = new Node(1);
printTree(head7);
System.out.println(isBST(head7));
Node res7 = recoverTree(head7);
printTree(res7);
System.out.println(isBST(res7));
// 情况8, 8 -> e1, 7 -> e2
System.out.println("situation 8");
Node head8 = new Node(5);
head8.left = new Node(3);
head8.right = new Node(8);
head8.left.left = new Node(2);
head8.left.right = new Node(4);
head8.right.left = new Node(6);
head8.right.right = new Node(7);
head8.left.left.left = new Node(1);
printTree(head8);
System.out.println(isBST(head8));
Node res8 = recoverTree(head8);
printTree(res8);
System.out.println(isBST(res8));
// 情况9, 3 -> e1, 2 -> e2
System.out.println("situation 9");
Node head9 = new Node(5);
head9.left = new Node(2);
head9.right = new Node(7);
head9.left.left = new Node(3);
head9.left.right = new Node(4);
head9.right.left = new Node(6);
head9.right.right = new Node(8);
head9.left.left.left = new Node(1);
printTree(head9);
System.out.println(isBST(head9));
Node res9 = recoverTree(head9);
printTree(res9);
System.out.println(isBST(res9));
// 情况10, 7 -> e1, 6 -> e2
System.out.println("situation 10");
Node head10 = new Node(5);
head10.left = new Node(3);
head10.right = new Node(6);
head10.left.left = new Node(2);
head10.left.right = new Node(4);
head10.right.left = new Node(7);
head10.right.right = new Node(8);
head10.left.left.left = new Node(1);
printTree(head10);
System.out.println(isBST(head10));
Node res10 = recoverTree(head10);
printTree(res10);
System.out.println(isBST(res10));
// 情况11, 6 -> e1, 2 -> e2
System.out.println("situation 11");
Node head11 = new Node(5);
head11.left = new Node(3);
head11.right = new Node(7);
head11.left.left = new Node(6);
head11.left.right = new Node(4);
head11.right.left = new Node(2);
head11.right.right = new Node(8);
head11.left.left.left = new Node(1);
printTree(head11);
System.out.println(isBST(head11));
Node res11 = recoverTree(head11);
printTree(res11);
System.out.println(isBST(res11));
// 情况12, 8 -> e1, 2 -> e2
System.out.println("situation 12");
Node head12 = new Node(5);
head12.left = new Node(3);
head12.right = new Node(7);
head12.left.left = new Node(8);
head12.left.right = new Node(4);
head12.right.left = new Node(6);
head12.right.right = new Node(2);
head12.left.left.left = new Node(1);
printTree(head12);
System.out.println(isBST(head12));
Node res12 = recoverTree(head12);
printTree(res12);
System.out.println(isBST(res12));
// 情况13, 6 -> e1, 4 -> e2
System.out.println("situation 13");
Node head13 = new Node(5);
head13.left = new Node(3);
head13.right = new Node(7);
head13.left.left = new Node(2);
head13.left.right = new Node(6);
head13.right.left = new Node(4);
head13.right.right = new Node(8);
head13.left.left.left = new Node(1);
printTree(head13);
System.out.println(isBST(head13));
Node res13 = recoverTree(head13);
printTree(res13);
System.out.println(isBST(res13));
// 情况14, 8 -> e1, 4 -> e2
System.out.println("situation 14");
Node head14 = new Node(5);
head14.left = new Node(3);
head14.right = new Node(7);
head14.left.left = new Node(2);
head14.left.right = new Node(8);
head14.right.left = new Node(6);
head14.right.right = new Node(4);
head14.left.left.left = new Node(1);
printTree(head14);
System.out.println(isBST(head14));
Node res14 = recoverTree(head14);
printTree(res14);
System.out.println(isBST(res14));
}
}
