[POJ][1009]Edge Detection

最新推荐文章于 2021-03-26 19:53:09 发布

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最新推荐文章于 2021-03-26 19:53:09 发布 · 2.6k 阅读

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#poj #源代码

本文介绍了POJ 1009题目的解决方案，重点在于如何处理大规模数据并避免超时。通过证明输出起始点必定临近输入起始点，采用模拟方法，并利用二维数组存储数据。详细讲解了找到输出起始点的过程，包括计算边界值、处理边缘情况以及如何确保不会遗漏点。最后，通过结构体排序和特定比较函数找出连续边界值的个数，给出AC代码。

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Description

IONU Satellite Imaging, Inc. records and stores very large images using run length encoding. You are to write a program that reads a compressed image, finds the edges in the image, as described below, and outputs another compressed image of the detected edges.
A simple edge detection algorithm sets an output pixel's value to be the maximum absolute value of the differences between it and all its surrounding pixels in the input image. Consider the input image below:

The upper left pixel in the output image is the maximum of the values |15-15|,|15-100|, and |15-100|, which is 85. The pixel in the 4th row, 2nd column is computed as the maximum of |175-100|, |175-100|, |175-100|, |175-175|, |175-25|, |175-175|,|175-175|, and |175-25|, which is 150.
Images contain 2 to 1,000,000,000 (10 ⁹) pixels. All images are encoded using run length encoding (RLE). This is a sequence of pairs, containing pixel value (0-255) and run length (1-10 ⁹). Input images have at most 1,000 of these pairs. Successive pairs have different pixel values. All lines in an image contain the same number of pixels.

Input

Input consists of information for one or more images.