HDU 2036 reform Spring breeze blowing everywhere (calculate geometry)

Test instructions: you know.

Analysis: There is nothing to say, to find the area with a fork, try not to use Helen Formula, because the computational capacity is large, but also the loss of precision.

The code is as follows:

#include <iostream> #include <cstdio> #include <cstring> #include <queue> #include <set># Include <vector> #include <algorithm>using namespace Std;const int maxn = + 5;int X[MAXN], y[maxn];int Cros s (int x1, int y1, int x2, int y2) {    return x1 * y2-x2 * y1;} int main () {    int n;    while (scanf ("%d", &n) = = 1 && N) {        for (int i = 0; i < n; ++i)  scanf ("%d%d", &x[i], &y[i]); C6/>x[n] = x[0];  Y[n] = y[0];        double s = 0.0;        for (int i = 0; i < n; ++i)  S + = Cross (X[i], y[i], x[i+1], y[i+1]);        printf ("%.1lf\n", s/2.0);}    }

HDU 2036 reform Spring breeze blowing everywhere (calculate geometry)