merge_intervals.py

def merge(intervals):
    """
    :type intervals: List[List[int]]
    :rtype: List[List[int]]
    """
    #!NEETCODE
    intervals.sort(key = lambda i: i[0])
    res = [intervals[0]]

    for start,end in intervals[1:]:
        last_end = res[-1][1]

        if start<=last_end:
            res[-1][1] = max(end, last_end)
        else:
            res.append([start,end])
    return res




    """ save = intervals[0][1] #!MY WAY
    sv_post = 0
    res = [[]]*(len(intervals))
    res[0].append(intervals[0])
    for i in range(1,len(intervals)):
        if save >= intervals[i][0]:
            j = i
            while j>0:
                del res[j]
                j-=1
            res[i].append([intervals[sv_post][0],intervals[i][1]])
            save = intervals[i][1]
        res[i].append([intervals[i][0],intervals[i][1]])
    return res """

""" if len(intervals) == 1: #!CORRECT IMPLEMENTATION OF MY IDEA
    return intervals
        
     stack = [] #!c
    
    intervals.sort()
    
    i = 0
    stack.append([intervals[0][0], intervals[0][1]])
    
    while i < len(intervals)-1:
        curr = stack[-1]
        start = curr[0]
        end = curr[1]
        
        nxt = intervals[i+1]
        
        if end >= nxt[0]: # Conflict
            if end >= nxt[1]: # Full
                i += 1
                continue # No change
            stack.pop()
            stack.append([start, nxt[1]])
            i +=1
            continue
        
        stack.append( [nxt[0], nxt[1]] )
        continue
        
    return stack """