Codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
来源:互联网 发布:手机淘宝4.0.1 编辑:程序博客网 时间:2024/05/22 06:58
There are some beautiful girls in Arpa’s land as mentioned before.
Once Arpa came up with an obvious problem:
Given an array and a number x, count the number of pairs of indices i, j (1 ≤ i < j ≤ n) such that , where is bitwise xoroperation (see notes for explanation).
Immediately, Mehrdad discovered a terrible solution that nobody trusted. Now Arpa needs your help to implement the solution to that problem.
First line contains two integers n and x (1 ≤ n ≤ 105, 0 ≤ x ≤ 105) — the number of elements in the array and the integer x.
Second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 105) — the elements of the array.
Print a single integer: the answer to the problem.
2 31 2
1
6 15 1 2 3 4 1
2
In the first sample there is only one pair of i = 1 and j = 2. so the answer is 1.
In the second sample the only two pairs are i = 3, j = 4 (since ) and i = 1, j = 5 (since ).
A bitwise xor takes two bit integers of equal length and performs the logical xor operation on each pair of corresponding bits. The result in each position is 1 if only the first bit is 1 or only the second bit is 1, but will be 0 if both are 0 or both are 1. You can read more about bitwise xor operation here: https://en.wikipedia.org/wiki/Bitwise_operation#XOR.
题意:
给定的 n 个数中,当前第 i 个数和 i 之后的数 j ,满足 i xor j == x 的组数。
思路:
比赛的时候模拟的不够好。
应用 xor(异或)满足 a xor b = c ;b xor c = a 的性质,这个性质怎么会忘记呢!
AC CODE:
#include<stdio.h>#include<cstring>#include<algorithm>#define HardBoy main()#define ForMyLove return 0;using namespace std;const int MYDD = 1103 + 1e7;/*Bug -> 数组开 1e5 运行出错*/int a[MYDD];void Init() {for(int j = 0; j < MYDD; j++)a[j] = 0;}int HardBoy {int n, x;scanf("%d %d", &n, &x);Init();__int64 ans = 0;for(int j = 0; j < n; j++) {int k;scanf("%d", &k);ans += a[x xor k];a[k]++;}printf("%I64d\n", ans);ForMyLove}
被覆盖了!
- Codeforces 742B B. Arpa’s obvious problem and Mehrdad’s terrible solution
- 【codeforces 742B】Arpa’s obvious problem and Mehrdad’s terrible solution
- Codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution(map水题)
- Codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- CodeForces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- codeforces 742B - Arpa’s obvious problem and Mehrdad’s terrible solution
- CodeForces - 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- Codeforces 742B-Arpa’s obvious problem and Mehrdad’s terrible solution
- 742 B - Arpa’s obvious problem and Mehrdad’s terrible solution codeforces
- Codeforces Round #383 (Div. 2) 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- Codeforces 742 B. Arpa’s obvious problem and Mehrdad’s terrible solution
- Codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- CodeForces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- Arpa’s obvious problem and Mehrdad’s terrible solution CodeForces
- Arpa’s obvious problem and Mehrdad’s terrible solution (CodeForces
- B. Arpa’s obvious problem and Mehrdad’s terrible solution
- Codeforces Round #383 (Div. 2) B. Arpa’s obvious problem and Mehrdad’s terrible solution
- linux 环境变量问题
- log4j和其他日志框架桥接图
- java swap
- 什么是矢径
- Android 标签数字自定义控件
- Codeforces 742B Arpa’s obvious problem and Mehrdad’s terrible solution
- 使用CSocket、CSocketFile及CArchive组合接收不到数据的一种原因
- chrome 浏览器主页被 360 篡改解决办法
- 通过Github与PM2部署Node应用
- 基于Jtopo的网络拓扑编辑器初探
- 解决ES数据偏移问题
- 一句代码检测app新版本
- Intent传值新技能
- Java CountDownLatch