Consider this example: void send(int *to, int *from, int count) { int n = (count+7)/8; switch(count%8) { case 0: do{*to++ = *from++; case 7: *to++ = *from++; case 6: *to++ = *from++; case 5: *to++ = *from++; case 4: *to++ = *from++; case 3: *to++ = *from++; case 2: *to++ = *from++; case 1: *to++ … Read more
Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below. For example, given the following triangle [ [2], [3,4], [6,5,7], [4,1,8,3] ] The minimum path sum from top to bottom is 11 (i.e., 2 + 3 + 5 + 1 = … Read more
You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up: Could you do this in-place? In-place Solution By using the relation “matrix[i][j] = matrix[n-1-j][i]”, we can loop through the matrix. public void rotate(int[][] matrix) { int n = matrix.length; for (int i = 0; … Read more
Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has properties: 1) Integers in each row are sorted from left to right. 2) The first integer of each row is greater than the last integer of the previous row. For example, consider the following matrix: [ [1, … Read more
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order. For example, given the following matrix: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] You should return [1,2,3,6,9,8,7,4,5]. Java Solution 1 If more than one … Read more
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example, “Red rum, sir, is murder” is a palindrome, while “Programcreek is awesome” is not. Note: Have you consider that the string might be empty? This is a good question to ask during an interview. For the purpose … Read more
Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example, given [100, 4, 200, 1, 3, 2], the longest consecutive elements sequence should be [1, 2, 3, 4]. Its length is 4. Your algorithm should run in O(n) complexity. Java Solution 1 Because it requires O(n) complexity, we … Read more
Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Here are few examples. [1,3,5,6], 5 -> 2 [1,3,5,6], 2 -> 1 [1,3,5,6], 7 -> 4 … Read more
Given inorder and postorder traversal of a tree, construct the binary tree. Analysis This problem can be illustrated by using a simple example. in-order: 4 2 5 (1) 6 7 3 8 post-order: 4 5 2 6 7 8 3 (1) From the post-order array, we know that last element is the root. We can … Read more
Given a sorted linked list, delete all duplicates such that each element appear only once. For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3. Thoughts The key of this problem is using the right loop condition. And change what is necessary in each loop. You can use different iteration conditions like the following 2 … Read more
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In Java, you first write a .java file which is then compiled to .class file during compile time. Java is capable of loading classes at run time. The confusion is what is the difference between “load” and “initialize”. When and how is a Java class loaded and initialized? It can be clearly illustrated by using … Read more
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 … Read more
Given a binary tree, flatten it to a linked list in-place. For example, Given 1 / \ 2 5 / \ \ 3 4 6 The flattened tree should look like: 1 \ 2 \ 3 \ 4 \ 5 \ 6 Java Solution Go down the tree to the left, when the right child … Read more