ACM —— 1009 Edge Detection

解题代码：

package acm1009;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Main {

	static int mWidth, mHight;
	static int[][] pairs = new int[1009][2];
	static HashMap<Integer, Integer> outMap = new HashMap<Integer, Integer>();
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		while ((mWidth = stdin.nextInt()) != 0) {
			int num = 0;
			int totleLen = 0;
			outMap.clear();
			while (!(((pairs[num][0] = stdin.nextInt()) == 0)&((pairs[num][1] = stdin.nextInt()) == 0))) {
				totleLen += pairs[num++][1];
			}
			mHight = totleLen/mWidth;
			findEdges(num);
			outputImage(totleLen);
		}
		System.out.println("0");
	}
	
	private static void outputImage(int totleLen) {
		System.out.println(mWidth);
		Object[] keySet = outMap.keySet().toArray();
		Arrays.sort(keySet);
		int tempKey = Integer.parseInt(keySet[0].toString());
		int temp = outMap.get(tempKey);
		for (Object k : keySet) {
			int key = Integer.parseInt(k.toString());
			if (outMap.get(key) == temp) {
				continue;
			}
			System.out.println(temp + " " + (key -tempKey));
			temp = outMap.get(key);
			tempKey = key;
		}
		System.out.println(temp + " " + (totleLen -tempKey));
		System.out.println("0 0");
	}

	private static void findEdges(int num) {
		int pos = 0;
		int x,y;
		for (int p = 0; p <= num; p++) {
			x = pos/mWidth;
			y = pos%mWidth;
			for (int i = x-1; i <= x+1; i++) {
				if (i < 0|| i >= mHight) {
					continue;
				}
				for (int j = y-1; j <=y+1; j++) {
					if (j < 0||j >= mWidth) {
						continue;
					}
					int currPos = i*mWidth + j;
					outMap.put(currPos, getMaxValue(currPos));
				}
			}
			pos += pairs[p][1];
		}
	}
	
	private static Integer getMaxValue(int currPos) {
		int num=getnum(currPos),ret=0;
		   
	    int row=currPos/mWidth;
	    int col=currPos%mWidth;
	   
	    for (int i=row-1;i<=row+1;i++) {
			if (i < 0|| i >= mHight) {
				continue;
			}
	        for (int j=col-1;j<=col+1;j++)
	        {
	            int tpos= i*mWidth+j;
	            if (j<0||j>=mWidth|| tpos==currPos)
	                continue;
	               
	            int tmp=getnum(tpos);
	            if (Math.abs(tmp-num)>ret)ret=Math.abs(tmp-num);
	        }
	    }
	    return ret;
	}

	private static int getnum(int currPos) {
	    int p=0,i=0;
	    while (p<=currPos)
	        p+=pairs[i++][1];
	       
	    return pairs[i-1][0];
	}

}

注意* 跳跃式计算，第一个点和最后一个点要单算，不然会WA！