题目描述
输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下4 X 4矩阵： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
我的解答
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import java.util.ArrayList;
public class Solution {
private class Bounds{
int left, top, right, bottom;
}
public ArrayList<Integer> printMatrix(int [][] matrix) {
ArrayList<Integer> result = new ArrayList();
if (null == matrix || matrix.length == 0) {
return result;
} else {
//init
Bounds bounds = new Bounds();
bounds.left = bounds.top = 0;
bounds.bottom = matrix.length - 1;
bounds.right = matrix[0].length - 1;
while (bounds.left <= bounds.right || bounds.top <= bounds.bottom) {
if(visitTop(matrix, bounds, result)) break;
if (visitRight(matrix, bounds, result)) break;
if (visitBottom(matrix, bounds, result)) break;
if (visitLeft(matrix, bounds, result)) break;
}
return result;
}
}
/**
* 按顺序定义顺时针访问的四个方法
**/
private boolean visitTop(int [][] matrix, Bounds bounds, ArrayList<Integer> result) {
for (int i = bounds.left; i <= bounds.right; i++) {
result.add(new Integer(matrix[bounds.top][i]));
}
bounds.top++;
return bounds.top > bounds.bottom;
}
private boolean visitRight(int [][] matrix, Bounds bounds, ArrayList<Integer> result) {
for (int i = bounds.top; i <= bounds.bottom; i++) {
result.add(new Integer(matrix[i][bounds.right]));
}
bounds.right--;
return bounds.left > bounds.right;
}
private boolean visitBottom(int [][] matrix, Bounds bounds, ArrayList<Integer> result) {
for (int i = bounds.right; i >= bounds.left; i--) {
result.add(new Integer(matrix[bounds.bottom][i]));
}
bounds.bottom--;
return bounds.top > bounds.bottom;
}
private boolean visitLeft(int [][] matrix, Bounds bounds, ArrayList<Integer> result) {
for (int i = bounds.bottom; i >= bounds.top; i--) {
result.add(new Integer(matrix[i][bounds.left]));
}
bounds.left++;
return bounds.left > bounds.right;
}
}
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