添加 problem 56

Algorithms/56. Merge Intervals/56. Merge Intervals.go

@@ -0,0 +1,70 @@
+package leetcode
+
+/**
+ * Definition for an interval.
+ * type Interval struct {
+ *	   Start int
+ *	   End   int
+ * }
+ */
+
+type Interval struct {
+	Start int
+	End   int
+}
+
+func merge_(intervals []Interval) []Interval {
+	if len(intervals) == 0 {
+		return intervals
+	}
+	quickSort(intervals, 0, len(intervals)-1)
+	res := make([]Interval, 0)
+	res = append(res, intervals[0])
+	curIndex := 0
+	for i := 1; i < len(intervals); i++ {
+		if intervals[i].Start > res[curIndex].End {
+			curIndex++
+			res = append(res, intervals[i])
+		} else {
+			res[curIndex].End = max(intervals[i].End, res[curIndex].End)
+		}
+	}
+	return res
+}
+
+func max(a int, b int) int {
+	if a > b {
+		return a
+	} else {
+		return b
+	}
+}
+
+func min(a int, b int) int {
+	if a > b {
+		return b
+	} else {
+		return a
+	}
+}
+
+func partitionSort(a []Interval, lo, hi int) int {
+	pivot := a[hi]
+	i := lo - 1
+	for j := lo; j < hi; j++ {
+		if (a[j].Start < pivot.Start) || (a[j].Start == pivot.Start && a[j].End < pivot.End) {
+			i++
+			a[j], a[i] = a[i], a[j]
+		}
+	}
+	a[i+1], a[hi] = a[hi], a[i+1]
+	return i + 1
+}
+func quickSort(a []Interval, lo, hi int) {
+	if lo >= hi {
+		return
+	}
+	p := partitionSort(a, lo, hi)
+	quickSort(a, lo, p-1)
+	quickSort(a, p+1, hi)
+}

Algorithms/56. Merge Intervals/56. Merge Intervals_test.go

@@ -0,0 +1,72 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question56 struct {
+	para56
+	ans56
+}
+
+// para 是参数
+// one 代表第一个参数
+type para56 struct {
+	one []Interval
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans56 struct {
+	one []Interval
+}
+
+func Test_Problem56(t *testing.T) {
+
+	qs := []question56{
+
+		question56{
+			para56{[]Interval{}},
+			ans56{[]Interval{}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 1, End: 3}, Interval{Start: 2, End: 6}, Interval{Start: 8, End: 10}, Interval{Start: 15, End: 18}}},
+			ans56{[]Interval{Interval{Start: 1, End: 6}, Interval{Start: 8, End: 10}, Interval{Start: 15, End: 18}}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 1, End: 4}, Interval{Start: 4, End: 5}}},
+			ans56{[]Interval{Interval{Start: 1, End: 5}}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 1, End: 3}, Interval{Start: 3, End: 6}, Interval{Start: 5, End: 10}, Interval{Start: 9, End: 18}}},
+			ans56{[]Interval{Interval{Start: 1, End: 18}}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 15, End: 18}, Interval{Start: 8, End: 10}, Interval{Start: 2, End: 6}, Interval{Start: 1, End: 3}}},
+			ans56{[]Interval{Interval{Start: 1, End: 6}, Interval{Start: 8, End: 10}, Interval{Start: 15, End: 18}}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 1, End: 3}, Interval{Start: 2, End: 6}, Interval{Start: 8, End: 10}, Interval{Start: 15, End: 18}}},
+			ans56{[]Interval{Interval{Start: 1, End: 6}, Interval{Start: 8, End: 10}, Interval{Start: 15, End: 18}}},
+		},
+
+		question56{
+			para56{[]Interval{Interval{Start: 1, End: 4}, Interval{Start: 1, End: 5}}},
+			ans56{[]Interval{Interval{Start: 1, End: 5}}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 56------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans56, q.para56
+		fmt.Printf("【input】:%v       【output】:%v\n", p, merge_(p.one))
+	}
+	fmt.Printf("\n\n\n")
+}

Algorithms/56. Merge Intervals/README.md

@@ -0,0 +1,27 @@
+# [56. Merge Intervals](https://leetcode.com/problems/merge-intervals/)
+
+## 题目
+
+Given a collection of intervals, merge all overlapping intervals.
+
+Example 1:  
+
+```
+Input: [[1,3],[2,6],[8,10],[15,18]]
+Output: [[1,6],[8,10],[15,18]]
+Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].
+```
+
+Example 2:  
+
+```
+Input: [[1,4],[4,5]]
+Output: [[1,5]]
+Explanation: Intervals [1,4] and [4,5] are considered overlapping.
+```
+
+## 题目大意
+
+合并给的多个区间，区间有重叠的要进行区间合并。
+
+思路，先按照区间起点进行排序。然后从区间起点小的开始扫描，依次合并每个有重叠的区间。