Valid Boomerang
Given an array points where points[i] = [xi, yi] represents a point on the X-Y plane, return true if these points are a boomerang.
A boomerang is a set of three points that are all distinct and not in a straight line.
Example 1:
Input: points = [[1,1],[2,3],[3,2]]
Output: true
Example 2:
Input: points = [[1,1],[2,2],[3,3]]
Output: false
Constraints:
points.length == 3
points[i].length == 2
0 <= xi, yi <= 100
思路一：用斜率比较
public static boolean isBoomerang(int[][] points) {
if ((points[0][0] == points[1][0] && points[0][1] == points[1][1]) || (points[0][0] == points[2][0] && points[0][1] == points[2][1]) ||
(points[1][0] == points[2][0] && points[1][1] == points[2][1])) {
return false;
}
double x1 = points[1][0] - points[0][0];
double x2 = points[2][0] - points[0][0];
double y1 = points[1][1] - points[0][1];
double y2 = points[2][1] - points[0][1];
if (y1 == 0 && y2 == 0) {
return false;
} else if (y1 == 0 || y2 == 0) {
return true;
}
double slopA = x1 / y1;
double slopB = x2 / y2;
return slopA != slopB;
}