// 步骤3：遍历排序后的位置，用单调栈判断独立车队
"Space regulations don't cover the new problems emerging - interference with astronomical observations, risk of collision in orbit, risk of stuff falling on our heads, and now it is becoming clear, atmospheric pollution," says Andy Lawrence, Professor of Astronomy at the University of Edinburgh.
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「如今有更多美國人在工作，比我們國家歷史上的任何時刻都還要多」
Stephen StaffordBBC News, South
* @param arr 待排序数组