56 accepted，手动实现了一遍快排

Author: aQua

Algorithms/0056.merge-intervals/merge-intervals.go

@@ -1,5 +1,7 @@
 package Problem0056
 
+import "math/rand"
+
 // Interval Definition for an interval.
 type Interval struct {
 	Start int
@@ -11,6 +13,8 @@ func merge(intervals []Interval) []Interval {
 		return intervals
 	}
 
+	quickSort(intervals)
+
 	res := make([]Interval, 0, len(intervals))
 	temp := intervals[0]
 
@@ -29,7 +33,7 @@ func merge(intervals []Interval) []Interval {
 }
 
 func isOverlap(a, b Interval) bool {
-	return (a.Start <= b.Start && b.Start <= a.End) || (a.Start <= b.End && b.End <= a.End) || (b.Start <= a.Start && a.Start <= b.End)
+	return (a.Start <= b.Start && b.Start <= a.End) || (a.Start <= b.End && b.End <= a.End)
 }
 
 func mergeInterval(a, b Interval) Interval {
@@ -52,3 +56,34 @@ func max(a, b int) int {
 	}
 	return b
 }
+func quickSort(is []Interval) {
+	if len(is) <= 1 {
+		return
+	}
+
+	j := rand.Intn(len(is))
+	is[0], is[j] = is[j], is[0]
+	j = partition(is)
+	quickSort(is[0:j])
+	quickSort(is[j+1:])
+}
+
+//partition 要考虑好，当a.Len()==2时，如何排好序
+func partition(is []Interval) int {
+	i, j := 1, len(is)-1
+	for {
+		for is[0].Start >= is[i].Start && i < len(is)-1 {
+			i++
+		}
+		for is[j].Start >= is[0].Start && j > 0 {
+
+			j--
+		}
+		if i >= j {
+			break
+		}
+		is[i], is[j] = is[j], is[i]
+	}
+	is[0], is[j] = is[j], is[0]
+	return j
+}

Algorithms/0056.merge-intervals/merge-intervals_test.go

@@ -45,11 +45,11 @@ func Test_Problem0056(t *testing.T) {
 		question{
 			para{[]Interval{
 				Interval{1, 4},
-				Interval{0, 5},
+				Interval{0, 6},
 			},
 			},
 			ans{[]Interval{
-				Interval{0, 5},
+				Interval{0, 6},
 			},
 			},
 		},