- 2SumUniquePairs
import java.util.HashMap;
import java.util.Map;
public class twoSumUnique {
public static int uniquepairs(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return 0;
}
int res = 0;
Map<Integer, Boolean> mapForPrev = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
int diff = target - nums[i];
if (mapForPrev.containsKey(diff)) {
if (!mapForPrev.get(diff)) {
mapForPrev.put(diff, true);
res++;
}
mapForPrev.put(nums[i], true);
} else {
mapForPrev.put(nums[i], false);
}
}
return res;
}
public static void main(String[] args) {
int[] nums1 = { 1, 1, 2, 45, 46, 46 };
int target1 = 47;
System.out.println(uniquepairs(nums1, target1));
System.out.println("-------------------------------");
int[] nums2 = {1, 5, 1, 5};
int target2 = 6;
System.out.println(uniquepairs(nums2, target2));
}
}
- SubTree
public class subtree {
public boolean isSubtree(TreeNode s, TreeNode t){
return isSubtree(s, t, false);
}
public boolean isSubtree(TreeNode s, TreeNode t, boolean flag) {
if (s == null || t == null) {
if (s == null && t == null) {
return true;
} else {
return false;
}
}
if (s.val != t.val && flag){
return false;
}
if (s.val == t.val) {
flag = true;
if (isSubtree(s.left, t.left, true) && isSubtree(s.right, t.right, true)) {
return true;
}
}
return isSubtree(s.left, t, false) || isSubtree(s.right, t, false);
}
}
class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}
- Search 2D
public class search2D {
public boolean searchMatrix(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0) {
return false;
}
int row = matrix.length, col = matrix[0].length;
int i = 0, j = col - 1;
while (i < row && j >= 0) {
if (matrix[i][j] == target) {
return true;
} else if (matrix[i][j] < target) {
i++;
} else if (matrix[i][j] > target) {
j--;
}
}
return false;
}
}
- Spiral Matrix
public class spiralMatrix {
public int[][] generateMatrix(int n) {
int[][] res = new int[n][n];
if (n <= 0) {
return res;
}
int rowBegin = 0, rowEnd = n - 1;
int colBegin = 0, colEnd = n - 1;
int num = 1;
while (rowBegin <= rowEnd && colBegin <= colEnd) {
for (int j = colBegin; j <= colEnd; j++) {
res[rowBegin][j] = num++;
}
rowBegin++;
for (int i = rowBegin; i <= rowEnd; i++) {
res[i][colEnd] = num++;
}
colEnd--;
for (int k = colEnd; k >= colBegin; k--) {
res[rowEnd][k] = num++;
}
rowEnd--;
for (int m = rowEnd; m >= rowBegin; m--) {
res[m][colBegin] = num++;
}
colBegin++;
}
return res;
}
}
- Merge 2 sorted Linked List
//import java.util.LinkedList;
public class mergeTwoLists {
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
if (l1 == null) {
return l2;
} else if (l2 == null) {
return l1;
}
ListNode dummy = new ListNode(0);
ListNode prev = dummy;
while (l1 != null && l2 != null) {
if (l1.val <= l2.val) {
prev.next = l1;
l1 = l1.next;
} else {
prev.next = l2;
l2 = l2.next;
}
prev = prev.next;
}
if (l1 != null) {
prev.next = l1;
}
if (l2 != null) {
prev.next = l2;
}
return dummy.next;
}
}
class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}
- Copy Random Pointer
import java.util.*;
class Node {
public int val;
public Node next;
public Node random;
public Node() {}
public Node(int _val,Node _next,Node _random) {
val = _val;
next = _next;
random = _random;
}
};
public class copyRandomPointer {
public Node copyRandomList(Node head) {
if (head == null) {
return null;
}
Node temp = head;
while (temp != null) {
Node next = temp.next;
temp.next = new Node(temp.val, null, null);
temp.next.next = next;
temp = next;
}
temp = head;
while (temp != null) {
if (temp.random != null) {
temp.next.random = temp.random.next;
}
temp = temp.next.next;
}
temp = head;
Node copyHead = head.next;
Node copy = copyHead;
while (copy.next != null) {
temp.next = temp.next.next;
temp = temp.next;
copy.next = copy.next.next;
copy = copy.next;
}
temp.next = temp.next.next;
return copyHead;
}
}
- Critical Connections
- Favorite Geren
