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Summarize the four traversal methods of binary tree, using recursion and iteration. The recursive code is relatively simple, and the iterative code is relatively complex. 1, Preorder traversal (here, take the printed results as an example, you can also use ArrayList to store the val in the subtree) thinking Recursion: first the root node ...

Question 1 (corresponding to question 20 of LeetCode question bank) (simple question!) (of course, if you don't understand your own summary, you can go to the website and read the corresponding topic to see the solution!) Title: valid parentheses (parenthesis matching problem of string) (I wrote a hundred lines at the first time, but I could ...

PS: Sword finger offer is not only an interview guide that many students will refer to when looking for a job, but also an algorithm Guide (the main reason why it is so popular is that it provides a step-by-step optimization solution, which I think is very friendly). Now many Internet algorithm interview questions can be found here. For the con ...

Title Link The original question is linked in Non zero segment division , I won't post the title. Given an array, you can divide the array into as many continuous non-zero segments as possible by changing the number below the threshold into 0. Topic analysis A very direct idea is: there are m different non-zero values in the array with l ...

JavaScript data structure and algorithm (VI) one way linked list Cognitive linked list Linked lists and arrays Like arrays, linked lists can be used to store a series of elements, but the implementation mechanism of linked lists and arrays is completely different. array Storing multiple elements, arrays (or lists) are probably the most co ...

131. The largest rectangle in the histogram - AcWing question bank Title Description tag: monotone stack A histogram is a polygon consisting of a series of rectangles aligned at a common baseline. Rectangles have equal widths, but can have different heights. For example, the left side of the legend shows a histogram composed of rect ...

preface We often use cache to improve data query speed. Due to the limited cache capacity, when the cache capacity reaches the upper limit, we need to delete some data to make room so that new data can be added. Cache data cannot be deleted randomly. Generally, we need to delete cache data according to some algorithm. Common elimination algori ...

1, Algorithm principle 1. Principle overview    the point cloud data set generated by lidar sometimes receives echo signals incorrectly, which will lead to some wrong values. Due to the influence of measurement errors caused by scanning results, errors will inevitably occur in other processing of the point cloud, and some noise ...

LeetCode 15 sum of three numbers Title Description Give you an array num containing n integers. Judge whether there are three elements a, b and c in num, so that a + b + c = 0? Please find all triples with sum 0 and no repetition. OJ link Train of thought analysis First, special cases shall be handled If the array is empty, an empty c ...

(Kago double pointer chapter punch in) 1. Remove element thinking It can be solved directly. But the time complexity will be very large. A simpler way is to speed the pointer. The idea of this fast and slow pointer is that the slow pointer points to the position of the inserted character (treat the array as a new array), and the fast poi ...