zoukankan      html  css  js  c++  java
  • HDOJ 1071

    View Code
    Problem Description
    
     Ignatius bought a land last week, but he didn't know the area of the land because the land is enclosed by a parabola and a straight line. The picture below shows the area. Now given all the intersectant points shows in the picture, can you tell Ignatius the area of the land?
    
    Note: The point P1 in the picture is the vertex of the parabola.
    
    
    
    
     
    Input
    
     The input contains several test cases. The first line of the input is a single integer T which is the number of test cases. T test cases follow.
    Each test case contains three intersectant points which shows in the picture, they are given in the order of P1, P2, P3. Each point is described by two floating-point numbers X and Y(0.0<=X,Y<=1000.0).
     
    
    Output
    
     For each test case, you should output the area of the land, the result should be rounded to 2 decimal places.
     
    
    Sample Input
    
    2
    5.000000 5.000000
    0.000000 0.000000
    10.000000 0.000000
    10.000000 10.000000
    1.000000 1.000000
    14.000000 8.222222
    
     Sample Output
    
    33.33
    40.69
    
     Hint
    
     For float may be not accurate enough, please use double instead of float
    #include<stdio.h>
    #include<math.h>
    int main()
    {
        int T;
        double x1, x2, x3, y1, y2, y3, a, b, c, s;
        scanf("%d",&T);
        while(T--)
        {
            scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
            a = ((y2-y1)*(x3-x2)/(x2-x1)-(y3-y2))/((x2*x2-x1*x1)*(x3-x2)/(x2-x1)-(x3*x3-x2*x2));
            b = ((y2-y1)-a*(x2*x2-x1*x1))/(x2-x1);
            c = y1-a*x1*x1-b*x1;
            s = (a/3*x3*x3*x3+b/2*x3*x3+c*x3)-(a/3*x2*x2*x2+b*x2*x2/2+c*x2)-(y3+y2)*(x3-x2)/2;
            printf("%.2lf\n",s);
        }
        return 0;
    }

    比赛的时候这道题目我只用了不到十分钟,读题加AC不到十分钟,其实它很简单,很普通的算术题,没有任何算法在里面,看到大家都不去做这道题,我觉得可能是大家在研究算法的时候慢慢忽略了数学这一领域了吧,遇到高中时就滚瓜烂熟的数学题,却不敢去解了。我的算法学的不好,但是却时常会在题目中考虑是不是可以用数学的知识解答,而且很多题目中确实只用到数学理论就可以通过,但是算法中却没有这些。

  • 相关阅读:
    号称简明实用的django上手教程
    转先验概率、最大似然估计、贝叶斯估计、最大后验概率
    转基于概率的矩阵分解原理详解(PMF)
    转浅谈矩阵分解在推荐系统中的应用
    转推荐算法——基于矩阵分解的推荐算法
    代码生成器的需求
    兼容性的设计要求
    API设计的需求
    有关表单的需求梳理
    element-ui table 点击分页table滚到顶部
  • 原文地址:https://www.cnblogs.com/SDUTYST/p/2626200.html
Copyright © 2011-2022 走看看