AMC 8 1988 Problem 16
AMC8 1988 年第 16 题
鸽巢原理与策略★★★☆☆
Placing no more than one in each small square, what is the greatest number of 's that can be put on the grid shown without getting three 's in a row vertically, horizontally, or diagonally?
每个小方格最多放一个 ，在所示网格上最多能放多少个 ，使得任意垂直、水平或对角线方向不会出现连续的三个 ？
- A.2
- B.3
- C.4
- D.5
- E.6
正确答案 · Correct Answer
E
解析 · Solution
Solution 1
It is impossible to place 7 or more X's, as there would be 2 or fewer empty squares and thus not every row could have an empty square.
It is possible to place 6 X's as follows:
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