Given an integer array in the construct method, implement two methods query(start, end) and modify(index, value): For query(start, end), return the sum from index start to index end in the given array. For modify(index, value), modify the number in t…

Given n unique integers, number k (1<=k<=n) and target. Find all possible k integers where their sum is target. Example Given [1,2,3,4], k=2, target=5, [1,4] and [2,3] are possible solutions. 这道题同Combination Sum II public class Solution { /** * @par…

Given an integer array (index from 0 to n-1, where n is the size of this array), and an query list. Each query has two integers [start, end]. For each query, calculate the sum number between index start and end in the given array, return the result l…

C++ DFS class Solution { public: void help(vector<int> &a, int now, int sum, int target, vector<int> &path, vector<vector<int> > &ans, bool last) { if (sum > target) { return ; } if (now >= a.size()) { if (sum ==…

Sliding window doesn't work. So it is a typical partial_sum base solution. As below. However if you use a balanced binary search tree, you can get O(nlgn) - like std::set<int> class Solution { public: /** * @param A an integer array * @param start a…

Given an integer array (index from 0 to n-1, where n is the size of this array), and an query list. Each query has two integers [start, end]. For each query, calculate the sum number between index start and end in the given array, return the result l…

Subarray Sum Given an integer array, find a subarray where the sum of numbers is zero. Your code should return the index of the first number and the index of the last number. Example Given [-3, 1, 2, -3, 4], return [0, 2] or [1, 3]. 用hashmap来存从nums[0…

Continuous Subarray Sum II   Given an circular integer array (the next element of the last element is the first element), find a continuous subarray in it, where the sum of numbers is the biggest. Your code should return the index of the first number…

题目链接:Path Sum II | LeetCode OJ Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2],…

Path Sum II Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [[5,4,11,2],[5,8,4,5]] 分析: dfs求解即可…