Solution29.java

package com.usher.algorithm.offer;

import java.util.ArrayList;

/**
 * @Author: Usher
 * @Description:
 * 顺时针打印矩阵
 * col > startX * 2,row > startY * 2
 */
public class Solution29 {
    public ArrayList<Integer> printMatrix(int [][] matrix) {
        ArrayList<Integer> ret = new ArrayList<>();
        int r1 = 0, r2 = matrix.length - 1, c1 = 0, c2 = matrix[0].length - 1;
        while (r1 <= r2 && c1 <= c2) {
            for (int i = c1; i <= c2; i++)
                ret.add(matrix[r1][i]);
            for (int i = r1 + 1; i <= r2; i++)
                ret.add(matrix[i][c2]);
            if (r1 != r2)
                for (int i = c2 - 1; i >= c1; i--)
                    ret.add(matrix[r2][i]);
            if (c1 != c2)
                for (int i = r2 - 1; i > r1; i--)
                    ret.add(matrix[i][c1]);
            r1++; r2--; c1++; c2--;
        }
        return ret;
    }
}