Check If two Line segments Intersect

// Approach: Use cross-product orientation tests. Check if segments straddle each other; handle collinear edge cases.
// Time: O(1) Space: O(1)
class Solution {
    String doIntersect(int p1[], int q1[], int p2[], int q2[]) {
        int o1 = orientation(p1, q1, p2);
        int o2 = orientation(p1, q1, q2);
        int o3 = orientation(p2, q2, p1);
        int o4 = orientation(p2, q2, q1);

        // General case
        if (o1 != o2 && o3 != o4)
            return "true";

        // Special Cases
        // p1, q1 and p2 are collinear and p2 lies on segment p1q1
        if (o1 == 0 && onSegment(p1, p2, q1)) 
            return "true";

        // p1, q1 and q2 are collinear and q2 lies on segment p1q1
        if (o2 == 0 && onSegment(p1, q2, q1)) 
            return "true";

        // p2, q2 and p1 are collinear and p1 lies on segment p2q2
        if (o3 == 0 && onSegment(p2, p1, q2)) 
            return "true";

        // p2, q2 and q1 are collinear and q1 lies on segment p2q2
        if (o4 == 0 && onSegment(p2, q1, q2)) 
            return "true";

        // Doesn't fall in any of the above cases
        return "false";
    }
    
    int orientation(int[] p, int[] q, int[] r)
    {
        long val = (long)(q[1] - p[1]) * (r[0] - q[0]) - 
                (long)(q[0] - p[0]) * (r[1]- q[1]);
                
        if(val == 0)
            return 0; //collinear
            
        return (val > 0) ? 1 : 2; // clock or counterclockwise
    }
    
    boolean onSegment(int[] p, int[] q, int[] r)
    {
        if(q[0] <= Math.max(p[0], r[0]) && q[0] >= Math.min(p[0], r[0]) &&
           q[1] <= Math.max(p[1], r[1]) && q[1] >= Math.min(p[1], r[1]))
            return true;
            
        return false;
    }
}