[LeetCode 54] Spiral Matrix

题目链接：spiral-matrix

import java.util.ArrayList;
import java.util.List;

/**
 * 
		Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
		
		For example,
		Given the following matrix:
		
		[
		 [ 1, 2, 3 ],
		 [ 4, 5, 6 ],
		 [ 7, 8, 9 ]
		]
		You should return [1,2,3,6,9,8,7,4,5].
 *
 */

public class SpiralMatrix {

	
//	21 / 21 test cases passed.
//	Status: Accepted
//	Runtime: 170 ms
//	Submitted: 0 minutes ago

    static List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> orders = new ArrayList<Integer>();
        if(matrix.length == 0) return orders;
    	int m = matrix.length;
        int n = matrix[0].length;
        
        //			up
        // left				right
        //			down
        
        int left = 0;
        int right = n - 1;
        int up = 0;
        int down = m - 1;
        
        while(left <= right && up <= down) {
        	
        	for(int i = left; i <= right; i ++) {
        		orders.add(matrix[up][i]);
        	}
        	up ++;
        	
        	for(int i = up; i <= down; i ++) {
        		orders.add(matrix[i][right]);
        	}
        	right --;
        	
        	for(int i = right; i >= left && up <= down; i --) {
        		orders.add(matrix[down][i]);
        	}
        	down --;
        	
        	for(int i = down; i >= up && left <= right; i --) {
        		orders.add(matrix[i][left]);
        	}
        	left ++;
        }
        return orders;
        
    }
	public static void main(String[] args) {
//		int[][] matrix = {{1,2, 3}, {4, 5, 6}, {7, 8, 9}};
		int[][] matrix = {{2, 3}};
		for (int n : spiralOrder(matrix)) {
			System.out.print(n + ", ");
		}
		

	}

}

[LeetCode 54] Spiral Matrix

原文：http://blog.csdn.net/ever223/article/details/44542545