A boomerang is a set of 3 points that are all distinct and not in a straight line.
Given a list of three points in the plane, return whether these points are a boomerang.
Example 1:
Input: [[1,1],[2,3],[3,2]]
Output: true
Example 2:
Input: [[1,1],[2,2],[3,3]]
Output: false
Note:
points.length == 3
points[i].length == 2
0 <= points[i][j] <= 100
public class Solution {
public bool IsBoomerang(int[][] points) {
return (points[0][0] - points[1][0]) * (points[0][1] - points[2][1]) != (points[0][0] - points[2][0]) * (points[0][1] - points[1][1]);
}
}
Time Complexity: O(1)
Space Complexity: O(1)
Assuming three points are A, B, C.
The first idea is that, calculate the area of ABC.
The other idea is to calculate the slope of AB and AC.
K_AB = (p[0][0] - p[1][0]) / (p[0][1] - p[1][1])
K_AC = (p[0][0] - p[2][0]) / (p[0][1] - p[2][1])
We check if K_AB != K_AC, instead of calculating a fraction.