day3——两数之和

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// 小白一名,0算法基础,艰难尝试算法题中,若您发现本文中错误, 或有其他见解,往不吝赐教,感激不尽,拜谢. 领扣第2题今日算法题干 //给定一个整数数组和一个目标值,找出数组中和为目标值的两个数.//// 你可以假设每个输入只对应一种答案,且同样的元素不能被重复利用.//// 示例://// 给定 nums = [2, 7, 11, 15], target = 9//// 因为 nums[0] + nums[1] = 2 + 7 = 9// 所以返回 [0, 1] 初次尝试 /** 第…

给定数组A，大小为n，现给定数X，判断A中是否存在两数之和等于X

题目:给定数组A,大小为n,现给定数X,判断A中是否存在两数之和等于X 思路一: 1,先采用归并排序对这个数组排序, 2,然后寻找相邻<k,i>的两数之和sum,找到恰好sum>x的位置,如果sum=x则返回true, 3,找到位置后,保持i不变,从k处向前遍历,直到找到A[k]+A[i]等于x,并返回TRUE,如果找不到,则返回false. 论证步骤3:当前找到的位置恰好A[k]+A[i]>x,且前一位置的sum<x: 所以A[i]前面的数(不包括A[i])无论取哪两个数都…

LeetCode 170. Two Sum III - Data structure design （两数之和之三 - 数据结构设计）$

Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. For example, add(1); ad…

LeetCode 371. Sum of Two Integers （两数之和）

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example:Given a = 1 and b = 2, return 3. 题目标签:Bit Manipulation 这道题目让我们做两数之和,当然包括负数,而且不能用+,-等符号.所以明显是让我们从计算机的原理出发,运用OR,AND,XOR等运算法则.一开始自己想的如果两个数都是正数,那么很简单,…

LeetCode 167. Two Sum II - Input array is sorted （两数之和之二 - 输入的是有序数组）

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 m…

[LeetCode] Two Sum IV - Input is a BST 两数之和之四 - 输入是二叉搜索树

Given a Binary Search Tree and a target number, return true if there exist two elements in the BST such that their sum is equal to the given target. Example 1: Input: 5 / \ 3 6 / \ \ 2 4 7 Target = 9 Output: True Example 2: Input: 5 / \ 3 6 / \ \ 2 4…

[LeetCode] 1. Two Sum 两数之和

Part 1. 题目描述 (easy) 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 n…