POJ1088 滑雪 dp

DP第二题,做过很多次了,这次没用记忆化搜索,而是先排序之后for循环进行动态规划.

代码如下:

#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;

int N;

struct Point {
    double x, y;    
    void read() {
        scanf("%lf %lf", &x, &y);
    }
}p[105];

int main() {
    int T, ret, ca = 0;
    scanf("%d", &T);
    while (T--) {
        ret = 0x7fffffff+1;
        scanf("%d", &N);    
        for (int i = 0; i < N; ++i) {
            p[i].read();    
        }
        if (N == 1) {
            ret = 1;
        } else {
            for (int i = 0; i < N; ++i) {
                for (int j = i+1; j < N; ++j) { // 枚举出所有的直线 
                    int cnt = 2;
                    double x = p[j].x - p[i].x;
                    double y = p[j].y - p[i].y;
                    for (int k = j+1; k < N; ++k) {
                        double a = p[k].x - p[i].x;
                        double b = p[k].y - p[i].y;
                        if (fabs(x*b-y*a) < 1e-6) {
                            ++cnt;
                        }
                    }
                    ret = max(ret, cnt);
                }
            }
        }
        printf("Case %d: %d\n", ++ca, ret);
    }
    return 0;
}