add new solutions

solutions/9/q986/solution.go

@@ -0,0 +1,66 @@
+package q986
+
+import "slices"
+
+type listElem struct {
+	x       int
+	listId  int8 // 0, 1
+	isStart bool
+}
+
+func intervalIntersection(firstList [][]int, secondList [][]int) [][]int {
+	locations := make([]listElem, 0, len(firstList)*2+len(secondList)*2)
+
+	for i := range firstList {
+		locations = append(
+			locations,
+			listElem{x: firstList[i][0], listId: 0, isStart: true},
+			listElem{x: firstList[i][1], listId: 0, isStart: false},
+		)
+	}
+	for i := range secondList {
+		locations = append(
+			locations,
+			listElem{x: secondList[i][0], listId: 1, isStart: true},
+			listElem{x: secondList[i][1], listId: 1, isStart: false},
+		)
+	}
+	slices.SortFunc(locations, func(a, b listElem) int {
+		if a.x != b.x {
+			return a.x - b.x
+		}
+		if a.isStart {
+			return -1
+		}
+		return 1
+	})
+
+	ret := [][]int{}
+	start := 0
+	isA, isB := false, false
+	for _, loc := range locations {
+		if loc.isStart {
+			start = loc.x
+			switch loc.listId {
+			case 0:
+				isA = true
+			default:
+				isB = true
+			}
+		} else {
+			if isA && isB {
+				ret = append(ret, []int{start, loc.x})
+			}
+			switch loc.listId {
+			case 0:
+				isA = false
+			default:
+				isB = false
+			}
+		}
+	}
+
+	return ret
+}
+
+var _ = intervalIntersection