Discription Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Example: Given nums = [2…

转自  http://tech-wonderland.net/blog/summary-of-ksum-problems.html 前言: 做过leetcode的人都知道, 里面有2sum, 3sum(closest), 4sum等问题, 这些也是面试里面经典的问题, 考察是否能够合理利用排序这个性质, 一步一步得到高效的算法. 经过总结, 本人觉得这些问题都可以使用一个通用的K sum求和问题加以概括消化, 这里我们先直接给出K Sum的问题描述和算法(递归解法), 然后将这个一般性的方法套用…

Given a nested list of integers, return the sum of all integers in the list weighted by their depth. Each element is either an integer, or a list -- whose elements may also be integers or other lists. Different from the [leetcode]339. Nested List Wei…

Leetcode 931. Minimum falling path sum 最小下降路径和(动态规划) 题目描述 已知一个正方形二维数组A,我们想找到一条最小下降路径的和 所谓下降路径是指,从一行到下一行,只能选择间距不超过1的列(也就是说第一行的第一列,只能选择第二行的第一列和第二列:第二行的第二列,只能选择第三行的第一列第二列第三列),最小下降路径就是这个路径的和最小 测试样例 Input: [[1,2,3],[4,5,6],[7,8,9]] Output: 12 Explanation:…

题目 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, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…

Given an array nums and a target value k, find the maximum length of a subarray that sums to k. If there isn't one, return 0 instead. Example 1: Given nums = [1, -1, 5, -2, 3], k = 3,return 4. (because the subarray [1, -1, 5, -2] sums to 3 and is the…

463. Island Perimeterhttps://leetcode.com/problems/island-perimeter/就是逐一遍历所有的cell,用分离的cell总的的边数减去重叠的边的数目即可.在查找重叠的边的数目的时候有一点小技巧,就是沿着其中两个方向就好,这种题目都有类似的规律,就是可以沿着上三角或者下三角形的方向来做.一刷一次ac,但是还没开始注意codestyle的问题,需要再刷一遍. class Solution { public: int islandPerime…

https://leetcode.com/problems/count-of-range-sum/ Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive. Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), incl…

Given an array of integers nums and a positive integer k, find whether it's possible to divide this array into knon-empty subsets whose sums are all equal. Example 1: Input: nums = [4, 3, 2, 3, 5, 2, 1], k = 4 Output: True Explanation: It's possible…

Given an array with n integers, you need to find if there are triplets (i, j, k) which satisfies following conditions: 0 < i, i + 1 < j, j + 1 < k < n - 1 Sum of subarrays (0, i - 1), (i + 1, j - 1), (j + 1, k - 1) and (k + 1, n - 1) should be…