poj 1654 Area

最新推荐文章于 2020-04-14 23:20:30 发布

寒笑f

最新推荐文章于 2020-04-14 23:20:30 发布

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分类专栏： poj 文章标签： struct string file

本文链接：https://blog.youkuaiyun.com/stormdpzh/article/details/7762812

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本文介绍了一个通过叉积计算由字符序列指定路径形成的多边形面积的C++程序。该程序使用了结构体来定义点，并实现了点之间的加法和叉积运算，以逐步构建多边形并计算其面积。

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第一个几何题目。

叉积求面积。

/*
 * Author: stormdpzh
 * Created Time: 2012/7/19 12:49:54
 * File Name: poj_1654.cpp
 */
#include <iostream>
#include <cstdio>
#include <sstream>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <algorithm>
#include <functional>

#define sz(v) ((int)(v).size())
#define rep(i, n) for(int i = 0; i < n; i++)
#define repf(i, a, b) for(int i = a; i <= b; i++)
#define repd(i, a, b) for(int i = a; i >= b; i--)
#define out(n) printf("%d\n", n)
#define mset(a, b) memset(a, b, sizeof(a))
#define wh(n) while(1 == scanf("%d", &n))
#define whz(n) while(1 == scanf("%d", &n) && n != 0)
#define lint long long

using namespace std;

const int MaxN = 1 << 30;

struct Point
{
    lint x, y;
    
    Point() {}
    Point(lint _x, lint _y) : x(_x), y(_y) {}
};

Point operator + (const Point &p1, const Point &p2) 
{
    return Point(p1.x + p2.x, p1.y + p2.y);
}

lint operator * (const Point &p1, const Point &p2)
{
    return (p1.x * p2.y - p2.x * p1.y);
}

string str;
Point pre;

void gao()
{
    lint area = 0;
    rep(i, sz(str)) {
        Point now;
        bool flag = false;
        switch(str[i]) {
            case '8': now = pre + Point(0, 1);
                      break;
            case '2': now = pre + Point(0, -1);
                      break;
            case '4': now = pre + Point(-1, 0);
                      break;
            case '6': now = pre + Point(1, 0);
                      break;
            case '9': now = pre + Point(1, 1);
                      break;
            case '7': now = pre + Point(-1, 1);
                      break;
            case '1': now = pre + Point(-1, -1);
                      break;
            case '3': now = pre + Point(1, -1);
                      break;
            case '5': flag = true;
                      break;
        }
        if(flag) break;
        area += (pre * now);
        pre = Point(now.x, now.y);
    }
    
    if(area < 0) area = -area;
    if(area & 1)
        cout << area / 2 << ".5" << endl;
    else 
        cout << area / 2 << endl;
}

int main()
{
    int t;
    scanf("%d", &t);
    while(t--) {
        cin >> str;
        pre = Point(0, 0);
        gao();
    }
    return 0;
}