/*
* Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).
You may assume that the intervals were initially sorted according to their start times.
Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].
Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].
This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].
*/
/*
* source code from blog:
* http://simpleandstupid.com/2014/10/29/insert-interval-leetcode-%E8%A7%A3%E9%A2%98%E7%AC%94%E8%AE%B0/
*
*
*/
public static ArrayList insert(ArrayList intervals, Interval newInterval)
{
ArrayList result = new ArrayList();
foreach (Interval interval in intervals)
{
if(interval.end < newInterval.start){
result.Add(interval);
}else if(interval.start > newInterval.end){
result.Add(newInterval);
newInterval = interval;
}else if(interval.end >= newInterval.start ||
interval.start <= newInterval.end){
newInterval = new Interval(
Math.Min(interval.start, newInterval.start),
Math.Max(newInterval.end, interval.end));
}
}
result.Add(newInterval);
return result;
}
/*
* Julia's comment:
* 1. First, review the thought process:
* Go over all the intervals one by one; In each iteration,
* compare to the two intervals.
*
* 3 cases:
* case 1: the interval ends before new interval starts ->
* action: add the interval to the return result container
*
* case 2: the interval starts after new interval ends ->
* action: add new interval to the return result container,
* and set the interval as the new one
*
* case 3: the interval overlaps with new interval ->
* action: merge two intervals, and save it as
* new interval.
*
* 2. Secondly, the code has a few of issues. Let us improve the code.
* 1. Abstract code, no more interval word in variable name;
* 2. Make it easy to go over test cases;
* Case stands out easily in the code.
* Code is more testable.
*
* step 1: Make the function a simple math, not interval business.
* step 2: Two intervals, R1 (stands for come and go one in the loop),
* R2 (stand for extra range for next iteration).
*
* tip: R2 one can be understandable by going through the test cases:
* Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16]
* R1 R2
* [1,2] [4,9] -> R1 is added to return container: {[1,2]}
* [3,5] [4,9] -> R1 and R2 overlaps, then, R2 = [3,9]
* [6,7] [3,9] -> R1 and R2 overlaps, then, R2 = [3,9]
* [8,10] [3,9] -> R1 and R2 overlaps, then, R2 = [3, 10]
* [12, 16] [3,10] -> R2 is added to return container, so it is {[1,2],[3,10]};
* R2 = R1 = [12, 16]
* Now add R2 to the return container, so the result: {[1,2], [3,10], [12, 16]}
*/
public static ArrayList insert_B(ArrayList arry, Interval newOne)
{
ArrayList result = new ArrayList();
Interval R2 = newOne;
foreach (Interval R_i in arry)
{
Interval R1 = R_i; // Range 1, come and go
bool isR1R2 = R1.end < R2.start; // R1 is before R2
bool isR2R1 = R1.start > R2.end; // R2 is before R1
bool needMerge = R1.end >= R2.start || // R1 overlaps R2
R1.start <= R2.end;
if (isR1R2)
{
result.Add(R1);
}
else if (isR2R1)
{
result.Add(R2);
R2 = R1;
}
else if (needMerge)
{
R2 = new Interval(
Math.Min(R1.start, R2.start),
Math.Max(R1.end, R2.end));
}
}
result.Add(R2);
return result;
}