add merge-intervals

Author: freefcw

leetcode/merge-intervals.go

@@ -0,0 +1,51 @@
+package leetcode
+
+func qsort(intervals [][]int, low, high int) {
+	if low >= high {
+		return
+	}
+	base := intervals[low][0]
+
+	i := low + 1
+	j := high - 1
+	for {
+		for i <= j && intervals[i][0] < base {
+			i++
+		}
+		for i <= j && intervals[j][0] >= base {
+			j--
+		}
+		if i >= j {
+			break
+		}
+		// fmt.Printf("i %d j %d\n", i, j)
+		intervals[i], intervals[j] = intervals[j], intervals[i]
+	}
+	intervals[j], intervals[low] = intervals[low], intervals[j]
+	qsort(intervals, low, j)
+	qsort(intervals, j+1, high)
+}
+
+func merge(intervals [][]int) [][]int {
+	if len(intervals) == 0 {
+		return intervals
+	}
+	qsort(intervals, 0, len(intervals))
+	result := make([][]int, 0, len(intervals))
+	last := make([]int, 2)
+	last[0], last[1] = intervals[0][0], intervals[0][1]
+	for i := 1; i < len(intervals); i++ {
+		if isAdjacent(last, intervals[i]) {
+			// fmt.Printf("merge! %v %v\n", last, intervals[i])
+			if last[1] < intervals[i][1] {
+				last[1] = intervals[i][1]
+			}
+		} else {
+			result = append(result, last)
+			last = intervals[i]
+		}
+	}
+	result = append(result, last)
+
+	return result
+}

leetcode/merge-intervals_test.go

@@ -0,0 +1,64 @@
+package leetcode
+
+import "testing"
+
+func Test_merge_none(t *testing.T) {
+	data := [][]int{
+		[]int{1, 2},
+		[]int{3, 6},
+		[]int{8, 10},
+		[]int{15, 18},
+	}
+	result := merge(data)
+	actual := pairs_array(result)
+	expect := "[[1,2][3,6][8,10][15,18]]"
+
+	if actual != expect {
+		t.Errorf("expect: %s, actual: %s", expect, actual)
+	}
+}
+
+func Test_merge_front(t *testing.T) {
+	data := [][]int{
+		[]int{1, 3},
+		[]int{2, 6},
+		[]int{8, 10},
+		[]int{15, 18},
+	}
+	result := merge(data)
+	actual := pairs_array(result)
+	expect := "[[1,6][8,10][15,18]]"
+
+	if actual != expect {
+		t.Errorf("expect: %s, actual: %s", expect, actual)
+	}
+}
+
+func Test_merge_all(t *testing.T) {
+	data := [][]int{
+		[]int{1, 4},
+		[]int{4, 5},
+		[]int{5, 6},
+	}
+	result := merge(data)
+	actual := pairs_array(result)
+	expect := "[[1,6]]"
+
+	if actual != expect {
+		t.Errorf("expect: %s, actual: %s", expect, actual)
+	}
+}
+
+func Test_merge_inner(t *testing.T) {
+	data := [][]int{
+	    []int{1,4},
+	    []int{2,3},
+	}
+	result := merge(data)
+	actual := pairs_array(result)
+	expect := "[[1,4]]"
+
+	if actual != expect {
+		t.Errorf("expect: %s, actual: %s", expect, actual)
+	}
+}