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23 lines
1.5 KiB
HTML
23 lines
1.5 KiB
HTML
<!DOCTYPE html>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<h1>1127. ZigZagging on a Tree (30)</h1>
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<div id="problemContent">
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<p>Suppose that all the keys in a binary tree are distinct positive integers. A unique binary tree can be determined by a given pair of postorder and inorder traversal sequences. And it is a simple standard routine to print the numbers in level-order. However, if you think the problem is too simple, then you are too naive. This time you are supposed to print the numbers in "zigzagging order" -- that is, starting from the root, print the numbers level-by-level, alternating between left to right and right to left. For example, for the following tree you must output: 1 11 5 8 17 12 20 15.</p>
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<center><img src="http://nos.patest.cn/nc_ol5xekjcdy4.jpg"/></center>
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<p><b>
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Input Specification:
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</b></p>
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<p>Each input file contains one test case. For each case, the first line gives a positive integer N (<= 30), the total number of nodes in the binary tree. The second line gives the inorder sequence and the third line gives the postorder sequence. All the numbers in a line are separated by a space.</p>
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<p><b>
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Output Specification:
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</b></p>
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<p>For each test case, print the zigzagging sequence of the tree in a line. All the numbers in a line must be separated by exactly one space, and there must be no extra space at the end of the line.</p>
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<b>Sample Input:</b><pre>
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8
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12 11 20 17 1 15 8 5
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12 20 17 11 15 8 5 1
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</pre>
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<b>Sample Output:</b><pre>
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1 11 5 8 17 12 20 15
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</pre>
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</div> |