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首先,我們確定肯定能取出來4個數的和是15的倍數,比如2、3、4、6如果我們取出來超過4個的一組數,其中一組4個數的和是15的倍數,然後把另一個數與這4個中的數進行交換,新的4個數的和也是15的倍數,說明交換的這兩個數的…
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