836 finish

Author: aQua

Algorithms/0836.rectangle-overlap/rectangle-overlap.go

@@ -1,6 +1,20 @@
 package problem0836
 
 func isRectangleOverlap(rec1 []int, rec2 []int) bool {
-    
-	return false
+	// 把 rec 分别投影到水平轴和竖直轴上
+	h1, v1 := projecting(rec1)
+	h2, v2 := projecting(rec2)
+	// 两个投影线同时相交可以认为 rec 相交
+	return isLineOverlap(h1, h2) && isLineOverlap(v1, v2)
+}
+
+func projecting(rec []int) (h, v []int) {
+	h = []int{rec[0], rec[2]}
+	v = []int{rec[1], rec[3]}
+	return
+}
+
+func isLineOverlap(a, b []int) bool {
+	// 没有分开，就是相交
+	return !(a[1] <= b[0] || b[1] <= a[0])
 }