[理工] 鴿籠原理
How many numbers must be selected from the first 10 positive integers to
guarentee at least two pairs of these numbers add up to 10?
我的想法是:
S={1,2,3,4,5,6,7,8,9,10}
先將和為10的分成:{1,9}{2,8}{3,7}{4,6},另外{5}例外
考慮worst case:取到1,2,3,4,5，所以至少再取2個，必有2對和為10
這樣答案是7個數，可是問老師老師是說8個..8個嗎?
求解
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推
12/28 19:02, , 1F
12/28 19:02, 1F
推
12/28 19:03, , 2F
12/28 19:03, 2F
推
12/28 19:05, , 3F
12/28 19:05, 3F
推
12/28 19:14, , 4F
12/28 19:14, 4F
→
12/28 19:45, , 5F
12/28 19:45, 5F
→
12/28 20:07, , 6F
12/28 20:07, 6F
推
12/28 20:11, , 7F
12/28 20:11, 7F
→
12/28 20:19, , 8F
12/28 20:19, 8F
推
12/28 21:26, , 9F
12/28 21:26, 9F
→
12/28 22:10, , 10F
12/28 22:10, 10F
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