gridland metro hackerrank矩阵

def gridlandMetro(n, m, k, tracks):
    grid = [[0] * m for _ in range(n)]
    
    # 标记铁路轨道
    for track in tracks:
        row = track[0] - 1
        start = track[1] - 1
        end = track[2] - 1
        for col in range(start, end + 1):
            grid[row][col] = 1
    
    # 计算最大土地面积
    max_area = 0
    for row in grid:
        intervals = mergeIntervals(row)
        for interval in intervals:
            max_area += interval[1] - interval[0] + 1
    
    return max_area

# 合并区间
def mergeIntervals(row):
    intervals = []
    start = None
    for i in range(len(row)):
        if row[i] == 1:
            if start is None:
                start = i
        else:
            if start is not None:
                intervals.append((start, i - 1))
                start = None
    if start is not None:
        intervals.append((start, len(row) - 1))
    return intervals