Fzu problem 2110 Star (math AH)

Title Link: http://acm.fzu.edu.cn/problem.php?pid=2110

Problem Descriptionoverpower often go to the playground with classmates. They play and chat on the playground. One day, there is a lot of stars in the sky. Suddenly, one of overpower's classmates ask him: "How many acute triangles whose inner angles is less than" degrees (re Garding stars as points) can be found? Assuming all the stars is in the same plane ". him to solve this problem. Input

The first line of the input contains an integer T (t≤10), indicating the number of the test cases.

For each test case:

The first line contains one integer n (1≤n≤100), the number of stars.

The next n lines each contains a integers x and y (0≤|x|, |y|≤1,000,000) indicate the points, all the points is distinc T.

Outputfor each test case, output a integer indicating the total number of different acute triangles. Sample Input130 010 Output1 Source "Higher Education Cup" the third Fujian University student Program Design Contest
Test Instructions:

How many acute triangle are you looking for?

The code is as follows:

#include <cstdio> #include <cstring> #include <cmath>const double Pi=acos ( -1.0), struct node{double x, Y;} A[1017];d ouble init (Node A, Node B) {return sqrt ((a.x-b.x) * (a.x-b.x) + (A.Y-B.Y) * (A.Y-B.Y));}    BOOL OK (double a,double b,double c) {double aa,bb,cc;    Cc=acos ((a*a+b*b-c*c)/(2*a*b));    Bb=acos ((a*a+c*c-b*b)/(2*a*c));    Aa=acos ((b*b+c*c-a*a)/(2*b*c));    if (cc<pi/2.0 && aa<pi/2.0 && bb<pi/2.0) return 1; return 0;}    int main () {int t;    int n;    scanf ("%d", &t);        while (t--) {scanf ("%d", &n);        for (int i = 0; i < n; i++) {scanf ("%lf%lf", &a[i].x,&a[i].y);        } int ans=0; for (int i = 0, i < n; i++) {for (int j = i+1; J < N; j + +) {for (int k = j+1; K < n;                    k++) {Double AA = init (a[i],a[j]);                    Double BB = init (a[i],a[k]); Double cc = INIt (A[j],a[k]);                if (OK (AA,BB,CC)) ans++;    }}} printf ("%d\n", ans); } return 0;}

Fzu problem 2110 Star (math AH)