Programmer Think

100. Same tree Link: https://leetcode-cn.com/problems/same-tree/ See the link for the title description. Solution 1: breadth first search What took advantage of was the problem of traversing the binary tree just yesterday, so it was completed smoothly today. At the beginning, I wanted to complete the search with depth first, but the re ...

Question 1: Force deduction 232 questions Problem solving ideas: This is related to the characteristics of stacks and queues. As we all know, stacks meet the requirements of "first in and last out", while queues meet the requirements of "first in and first out", so smart humans think of using two stacks to realize queues. ...

Give you an integer array numbers with subscript starting from 1. The array has been arranged in non decreasing order. Please find two numbers in the array that meet the sum of addition and equal to the target number target. If the two numbers are numbers[index1] and numbers[index2] respectively, then 1 < = index1 < index2 < = numbers ...

Example 1: 77 combination 77. Portfolio This question is mainly to understand the basic use of backtracking algorithm. Take the given n=4,k=2 as an example (source: Code Capriccio) As can be seen from the above figure, the logic of the code is to insert for loop traversal in recursion. The exit condition of a recursive loop is when the path ...

LeetCode 69. Square root of X title link: Title Description: Implement the int sqrt(int x) function. Calculates and returns the square root of X, where x is a nonnegative integer. Since the return type is an integer, only the integer part of the result will be retained, and the decimal part will be rounded off. Example 1: Input: 4 Output ...

part1(1-500), part3(1000-*) 502. IPO Given k，w,profits Array and capital Array. k Indicates the maximum number of tasks that can be completed. w Is the initial capital. profits Is the benefit of each task. capital This is the initial funding required to start this task. After completing one task at a time, add the income to the capital. Ask ...

Title: Judge whether the string s contains the string p. The input takes up two lines: String s and string p. The output contains the starting subscript of string p in string s. if there are multiple matches, all of them will be output, and each output will occupy one line. Case: Input: ABABABA ABA Output: 0 2 4 Preliminarily explore t ...

Title: Please judge whether a Sudoku of {9 x 9 is effective. You only need to verify whether the numbers you have filled in are valid according to the following rules. The numbers ， 1-9 ， can only appear once in each line. The numbers ＾ 1-9 ＾ can only appear once in each column. The numbers ＾ 1-9 ＾ can only appear once in each ＾ 3x3 ＾ ...

Brush on the buckle these days Some binary tree problems, rely on the basis (pre order traversal ~ middle order traversal ~ subsequent traversal ~ sequence traversal) to solve the problem. Of course, there are many methods to solve the problem.    [introduce the basic traversal first] Preorder traversal The first step is to ...

Leetcode question brushing record: 1 sum of two numbers (array hash) Title stem: Given an integer array nums and an integer target value target, please find the two integers with and as the target value target in the array and return their array subscripts. You can assume that each input will correspond to only one answer. However, the sam ...