Q ← 线段列表
    
for segment in Q:
    b ← segment.begin.x  # 起点的x坐标
    e ← segment.end.x    # 终点的x坐标
    A[b]++
    A[e]--

for i ← 1 to N-1:
    A[i] ← A[i] + A[i-1]