1037. Valid Boomerang
Given an array points wherep o i n t s [ i ] = [ x i , y i ] points[i] = [x_i, y_i]points[i]=[xi,yi]represents a point on the X-Y plane, returntrue 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 < = x i , y i < = 100 0 <= x_i, y_i <= 1000<=xi,yi<=100
From: LeetCode
Link: 1036. Escape a Large Maze
Solution:
Ideas:
A boomerang needs:
- 3 distinct points
- not collinear
Using the triangle-area / cross-product check:
- if cross product is 0, the 3 points are on the same line
- otherwise, they form a boomerang
Because the problem guarantees exactly 3 points, this one check is enough.
Code:
boolisBoomerang(int**points,intpointsSize,int*pointsColSize){intx1=points[0][0],y1=points[0][1];intx2=points[1][0],y2=points[1][1];intx3=points[2][0],y3=points[2][1];/* Three points are on one line if the area of the triangle is 0: (x2 - x1) * (y3 - y1) == (x3 - x1) * (y2 - y1) */return(x2-x1)*(y3-y1)!=(x3-x1)*(y2-y1);}
