RectangleOverlap.java

// Source : https://leetcode.com/problems/rectangle-overlap/
// Author : cornprincess
// Date   : 2020-03-18

/***************************************************************************************************** 
 *
 * A rectangle is represented as a list [x1, y1, x2, y2], where (x1, y1) are the coordinates of its 
 * bottom-left corner, and (x2, y2) are the coordinates of its top-right corner.
 * 
 * Two rectangles overlap if the area of their intersection is positive.  To be clear, two rectangles 
 * that only touch at the corner or edges do not overlap.
 * 
 * Given two (axis-aligned) rectangles, return whether they overlap.
 * 
 * Example 1:
 * 
 * Input: rec1 = [0,0,2,2], rec2 = [1,1,3,3]
 * Output: true
 * 
 * Example 2:
 * 
 * Input: rec1 = [0,0,1,1], rec2 = [1,0,2,1]
 * Output: false
 * 
 * Notes:
 * 
 * 	Both rectangles rec1 and rec2 are lists of 4 integers.
 * 	All coordinates in rectangles will be between -10^9 and 10^9.
 * 
 ******************************************************************************************************/

package RectangleOverlap;

public class RectangleOverlap {
    // check positon
    // Time and Space Complexity: O(1).
    public boolean isRectangleOverlap(int[] rec1, int[] rec2) {
        return !(rec2[2] <= rec1[0] || // rec2 is to the left of rec1
                rec2[0] >= rec1[2] || // rec2 is to the right of rec1
                rec2[1] >= rec1[3] || // rec2 is to the top of rec1
                rec2[3] <= rec1[1]); // rec2 is to the down of rec1
    }

    // check area
    // Time and Space Complexity: O(1).
    public boolean isRectangleOverlap2(int[] rec1, int[] rec2) {
        return (Math.min(rec1[2], rec2[2]) > Math.max(rec1[0], rec2[0]) &&
                Math.min(rec1[3], rec2[3]) > Math.max(rec1[1], rec2[1]));
    }
}