A Simple Task

本文解析了一道名为ASimpleTask的ACM编程题,题目要求输入一个正整数n,然后将其分解为一个奇数o乘以2的p次方的形式,并输出o和p的值。文中提供了一个C++实现的示例程序。

http://acm.hdu.edu.cn/showproblem.php?pid=1339

A Simple Task

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 4370    Accepted Submission(s): 2400


Problem Description
Given a positive integer n and the odd integer o and the nonnegative integer p such that n = o2^p.


Example

For n = 24, o = 3 and p = 3.


Task

Write a program which for each data set:

reads a positive integer n,

computes the odd integer o and the nonnegative integer p such that n = o2^p,

writes the result.
 

Input
The first line of the input contains exactly one positive integer d equal to the number of data sets, 1 <= d <= 10. The data sets follow.

Each data set consists of exactly one line containing exactly one integer n, 1 <= n <= 10^6.
 

Output
The output should consists of exactly d lines, one line for each data set.

Line i, 1 <= i <= d, corresponds to the i-th input and should contain two integers o and p separated by a single space such that n = o2^p.
 

Sample Input
  
1 24
 

Sample Output
  
3 3
 

Source
 

依据上述一个数只有唯一分解形式

#include <cstdio>
#define Max 1000000
int o[Max+10],p[Max+10];
void get_ans(void){
    for(int i=1;i<=Max;i++)
    {
        int x=2;
        int sum=0;
        while(i%x==0){x*=2;sum++;}
        x/=2;
        p[i]=sum;
        o[i]=i/x;

    }
}
int main()
{
    int t;
    get_ans();
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        printf("%d %d\n",o[n],p[n]);
    }
    return 0;
}


Plane geometry is an important branch of elementary mathematics. When Rikka was a middle school student, she learns a lot of theories about lines, triangles, and circles. As the time goes on, Rikka has learned a lot of more profound knowledge of mathematics, but she finds that the tasks about lines, triangles, and circles appear less and less. Rikka loves plane geometry because it is simple enough even for a middle school student and is interesting: she misses them very much. So, Rikka wants to come up with some tasks about lines for herself. She draws n lines y=aix+bi on the two-dimensional Cartesian coordinate system. And then she gives a rectangle with the left bottom corner (x1,y1) and the right top corner (x2,y2). She wants to count the number of the line pairs (i,j)(i<j) which satisfies their cross point (if exists) is inside the rectangle (including the boundary). It is a simple task for Rikka, and she wants to test you. To show your mathematics skill, you need to solve this task as soon as possible. Input The first line contains a single integer t(1≤t≤103), the number of the testcases. For each testcase, the first line contains five single integers n,x1,y1,x2,y2 which satisfy 1≤n≤105 and −109≤x1<x2≤109,−1018≤y1<y2≤1018. And then n lines follow, each line contains two integers ai,bi(−109≤ai≤109,ai≠0,−1016≤bi≤1016), describing a line. The input guarantees that each line is unique and there are at most 5 testcases with n>500. Output For each testcase, output a single line with a single number, the answer. Sample Input 1 4 0 0 2 2 2 -1 1 0 -1 2 2 2 Sample Output 4
最新发布
08-15
### 问题分析 HDU 6259 是一个与几何相关的算法题,题目要求统计在给定多个矩形的情况下,所有位于矩形内部的直线交点对的数量。每个矩形由其左下角和右上角坐标定义,而每对直线交点必须严格位于某个矩形内部才能被计入统计。 此问题涉及以下几个关键点: - **平面几何**:判断点是否在矩形内部。 - **数据结构**:高效存储和查询交点与矩形之间的关系。 - **组合数学**:统计交点对的数量,避免重复计数。 ### 算法设计 首先,需要找出所有直线之间的交点。对于每一对直线 $ L_1: a_1x + b_1y + c_1 = 0 $ 和 $ L_2: a_2x + b_2y + c_2 = 0 $,如果它们不平行(即 $ a_1b_2 \ne a_2b_1 $),则交点坐标为: $$ x = \frac{b_1c_2 - b_2c_1}{a_1b_2 - a_2b_1}, \quad y = \frac{a_2c_1 - a_1c_2}{a_1b_2 - a_2b_1} $$ 然后,对于每一个交点,遍历所有矩形,判断该点是否在矩形内部。矩形由左下角 $ (x_{min}, y_{min}) $ 和右上角 $ (x_{max}, y_{max}) $ 定义,点 $ (x, y) $ 在矩形内部的条件是: $$ x_{min} < x < x_{max}, \quad y_{min} < y < y_{max} $$ 为了避免重复统计交点对,可以使用哈希表记录每一对交点是否已经被计数。具体地,使用 `unordered_map` 或 `map` 存储交点坐标的浮点数表示(或使用分数形式避免精度误差),并为每个交点分配唯一标识符,再统计位于矩形内的交点对数。 ### 代码示例 以下是一个基于上述思路的 C++ 实现框架: ```cpp #include <bits/stdc++.h> using namespace std; struct Point { double x, y; bool operator<(const Point& p) const { if (x != p.x) return x < p.x; return y < p.y; } }; int main() { int n, m; cin >> n >> m; vector<tuple<double, double, double>> lines(n); for (int i = 0; i < n; ++i) { double a, b, c; cin >> a >> b >> c; lines[i] = make_tuple(a, b, c); } vector<tuple<double, double, double, double>> rects(m); for (int i = 0; i < m; ++i) { double x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2; rects[i] = make_tuple(min(x1, x2), min(y1, y2), max(x1, x2), max(y1, y2)); } map<Point, int> point_count; for (int i = 0; i < n; ++i) { for (int j = i + 1; j < n; ++j) { double a1, b1, c1, a2, b2, c2; tie(a1, b1, c1) = lines[i]; tie(a2, b2, c2) = lines[j]; double det = a1 * b2 - a2 * b1; if (det == 0) continue; double x = (b1 * c2 - b2 * c1) / det; double y = (a2 * c1 - a1 * c2) / det; Point p = {x, y}; point_count[p]++; } } int total = 0; for (const auto& p : point_count) { bool inside = false; for (const auto& rect : rects) { double x_min, y_min, x_max, y_max; tie(x_min, y_min, x_max, y_max) = rect; if (p.first.x > x_min && p.first.x < x_max && p.first.y > y_min && p.first.y < y_max) { inside = true; break; } } if (inside) { total += p.second; } } cout << total << endl; return 0; } ``` ### 时间与空间复杂度 - **时间复杂度**:最坏情况下为 $ O(n^2 + n^2 \cdot m) $,其中 $ n $ 是直线数量,$ m $ 是矩形数量。 - **空间复杂度**:取决于交点数量,最坏情况下为 $ O(n^2) $。 ### 注意事项 - **精度问题**:由于涉及浮点运算,建议使用 `double` 类型并注意精度控制。 - **避免重复计数**:使用 `map` 或 `unordered_map` 来记录交点是否已处理。 - **矩形判断优化**:可使用空间划分结构(如四叉树或网格划分)优化点与矩形的匹配过程。 ###
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