Fenwick Tree Input The first line of input contains two integers NN, QQ, where 1≤N≤50000001≤N≤5000000 is the length of the array and 0≤Q≤50000000≤Q≤5000000 is the number of operations. Then follow QQ lines giving the operations. There are two types o…
Motivation: Given a 1D array of n elements. [2, 5, -1, 3, 6] range sum query: what's the sum from 2nd element to 4th element query(2, 4)? 5 + (-1) + 3 = 7 Native implementation: O(n) per query. Use DP to pre-compute the prefix sums in O(n), [2, 5, -1…
You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smaller elements to the right of nums[i]. Example: Input: [5,2,6,1] Output:[5,2,6,1] Explanation: To the…
Fenwick Tree, (also known as Binary Indexed Tree,二叉索引树), is a high-performance data structure to calculate the sum of elements from the beginning to the indexed in a array. It needs three functions and an array: Array sum; It stores the data of Fenwi…
树状数组又称芬威克树,概念上是树状,实际上是使用数组实现的,表现为一种隐式数据结构,balabala...详情请见:https://en.wikipedia.org/wiki/Fenwick_tree 其中`i += (i & -i)`的相当于求 $ 2^{n-1} , n \in 1,2,3... $,还可以写成`i += (i & (i ^ (i - 1)))`. code: #include <iostream> #define LSB(i) (i & -i) c…
Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRange(0, 2) -> 9 update(1, 2…
传送门 The task is to find the length of the longest subsequence in a given array of integers such that all elements of the subsequence are sorted in ascending order. For example, the length of the LIS for { 15, 27, 14, 38, 26, 55, 46, 65, 85 } is 6 and…
QUESTION : What are the 10 algorithms one must know in order to solve most algorithm challenges/puzzles? ANSWER: Dynamic Programming (DP) appears to account for a plurality (some estimate up to a third) of contest problems. Of course, DP is also not…
Season 1, Episode 22: Flight -Franklin: You know you got a couple of foxes in your henhouse, right? fox: 狐狸 henhouse: 鸡舍 你的队伍里都是一群狐狸 -Michael: They both want out of here. both: 两者都 他们都想出去 They'll behave until then. behave: 举止端正 出去前都会安分的 -Franklin: Lo…
Almost identical to LintCode "Count of Smaller Number before Self". Corner case needs to be taken care of. class Solution { ////////////////// // Fenwick Tree // vector<long long> ft; void update(int i, long long x) { ) { ft[] ++; return;…
题目: Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2…
题目: Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRange(0, 2) -> 9 update(…
