题目链接:https://atcoder.jp/contests/abc129/tasks/abc129_e 题目大意 给定一个二进制表示的数 L,问有多少对自然数 (a, b) 满足 $a + b \leq L 且 a + b = a \oplus b $. 分析 由于异或是无进位相加,所以 $a + b = a \oplus b $ 等价于 a 和 b 的每一位对应二进制位都不会是两个 1. 设 L 有 n 个 1.按 L 中的顺序编号为 n~1. 设 L(i) 为编号为 i 的 1 到 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. Notice There is at least one subarray that it's sum equals to zero. Example…

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k.Example 1:Input:nums = [1,1,1], k = 2Output: 2Note:The length of the array is in range [1, 20,000].The range of numbers in th…

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. Example 1: Input:nums = [1,1,1], k = 2 Output: 2 Note: The length of the array is in range [1, 20,000]. The range of numbers…

Sum of xor jdoj-2160 题目大意:给你一个n,求1^2^...^n. 注释:$n<=10^{18}$. 想法:第一道异或的题.先来介绍一下什么是异或.a^b表示分别将两个数变成二进制后,从左到右按位取异或.两个异或字符,相同为0,不同为1.接下来,我们来证明异或的一些性质. 1.异或单位独立性.两个数的二进制,如果位数不够按位补全.我们显然可以证明,每一位上的异或显然独立的. 2.a^0=a,a^a=0.显然. 3.异或交换律.我们对于三个数来进行考虑.不妨设为a,b,c.我们…

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. Example 1: Input:nums = [1,1,1], k = 2 Output: 2 Note: The length of the array is in range [1, 20,000]. The range of numbers…

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. Example 1: Input:nums = [1,1,1], k = 2 Output: 2  Note: The length of the array is in range [1, 20,000]. The range of number…

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. Example 1: Input:nums = [1,1,1], k = 2 Output: 2 Note: The length of the array is in range [1, 20,000]. The range of numbers…

［抄题］: Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k. Example 1: Input:nums = [1,1,1], k = 2 Output: 2 [暴力解法]: 时间分析: 空间分析: [优化后]: 时间分析: 空间分析: ［奇葩输出条件］: ［奇葩corner case］: ［思维…

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. Notice There is at least one subarray that it's sum equals to zero. Example…