Q ← 線分の列
    
for segment in Q:
    b ← segment.begin.x  # 始点のx座標
    e ← segment.end.x    # 終点のx座標
    A[b]++
    A[e]--

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