57. Insert Interval

Medium

You are given an array of non-overlapping intervals intervals where intervals[i] = [starti, endi] represent the start and the end of the ith interval and intervals is sorted in ascending order by starti. You are also given an interval newInterval = [start, end] that represents the start and end of another interval.

Insert newInterval into intervals such that intervals is still sorted in ascending order by starti and intervals still does not have any overlapping intervals (merge overlapping intervals if necessary).

Return intervals after the insertion.

Example 1:

Input: intervals = [[1,3],[6,9]], newInterval = [2,5]
Output:
 [[1,5],[6,9]]

Example 2:

Input: intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
Output:
 [[1,2],[3,10],[12,16]]
Explanation:
 Because the new interval [4,8] overlaps with [3,5],[6,7],[8,10].

Constraints:

• 0 <= intervals.length <= 104

• intervals[i].length == 2

• 0 <= starti <= endi <= 105

• intervals is sorted by starti in ascending order.

• newInterval.length == 2

• 0 <= start <= end <= 105

解題

Runtime: 10 ms, faster than 81.36%

Memory Usage: 4.6 MB, less than 76.10%

第二次解

func insert(intervals [][]int, newInterval []int) [][]int {
    if len(intervals) == 0 { // intervals 中沒東西的情況
        return [][]int{ newInterval }
    }
 
    // 將新給的 interval 加入 intervals 陣列後重新進行排序
    intervals = append(intervals, newInterval)

    sort.Slice(intervals, func(i, j int) bool {
        if intervals[i][0] ==  intervals[j][0] {
            return intervals[i][1] < intervals[j][1]
        }
	return intervals[i][0] < intervals[j][0]
    })

    // stack
    ans := make([][]int, 0)
    ans = append(ans, intervals[0])
    
    // 每次插入新的 element 時做檢查
    for i:=1; i<len(intervals); i++ {
        last := ans[len(ans)-1]
        current := intervals[i]

        if current[0] > last[1] {
            ans = append(ans, current)
        } else { //current[0] <= last[1]
            if current[1] > last[1] {
                last[1] = current[1]
            }
        }
    }

    return ans
}