本文主要是介绍poj 1654 Area，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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 longusing 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;
}
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