UVA

最优三角剖分的变形

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <cmath>using namespace std;const double PI = acos(-1.0);const int maxn = 50;struct Point {    double x, y;    Point(double xx = 0, double yy = 0) : x(xx), y(yy) {}};typedef Point Vector;int n, m;double t, dp[maxn][maxn][maxn];Point p[maxn];Vector operator - (const Vector A, const Vector B) { return Vector(A.x-B.x, A.y-B.y); }double Cross(Vector A, Vector B) { return A.x*B.y-A.y*B.x; }double area(int x, int y, int z) {    return fabs(Cross(p[y] - p[x], p[z] - p[x])) / 2.0;}Vector Rotate(Vector A, double rad) {    return Vector(A.x*cos(rad)-A.y*sin(rad), A.x*sin(rad)+A.y*cos(rad));}int main() {    Vector base; base.x = 1, base.y = 0;    while (~scanf("%d %d", &n, &m) && (n + m)) {        for (int i = 1; i <= n; i++) {            scanf("%lf", &t); p[i] = Rotate(base, t * 2.0 * PI);        }        memset(dp, 0, sizeof(dp));        double ans = 0;        for (int num = 3; num <= m; num++) {            for (int len = 2; len < n; len++) {                for (int i = 1; i + len <= n; i++) {                    int j = i + len;                    for (int k = i + 1; k < j; k++) {                        dp[num][i][j] = max(dp[num][i][j], max(dp[num-1][i][k], dp[num-1][k][j]) + area(i, k, j));                    }                    ans = max(ans, dp[num][i][j]);                }            }        }        printf("%.6lf\n", ans);    }    return 0;}