leetcode-spiral-matrix-i-ii

public class  {
    public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> ans = new ArrayList<Integer>();
        if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
            return ans;
        }
        int m = matrix.length;
        int n = matrix[0].length;
        int up = 0; 
        int down = m - 1;
        int left = 0; 
        int right = n - 1;
        while (true) {
            for (int col = left; col <= right; col++) {
                ans.add(matrix[up][col]);
            }
            up++;
            if (up > down) {
                break;
            }
            for (int row = up; row <= down; row++) {
                ans.add(matrix[row][right]);
            }
            right--;
            if (right < left) {
                break;
            }
            for (int col = right; col >= left; col--) {
                ans.add(matrix[down][col]);
            }
            down--;
            if (down < up) {
                break;
            }
            for (int row = down; row >= up; row--) {
                ans.add(matrix[row][left]);
            }
            left++;
            if (left > right) {
                break;
            }
        }
        return ans;
    }
}

public class Solution {
    public int[][] generateMatrix(int n) {
        int[][] matrix = new int[n][n];
        int up = 0; 
        int down = n - 1;
        int left = 0; 
        int right = n - 1;
        int c = 0;
        while (true) {
            for (int col = left; col <= right; col++) {
                matrix[up][col] = ++c;
            }
            up++;
            if (up > down) {
                break;
            }
            for (int row = up; row <= down; row++) {
                matrix[row][right] = ++c;
            }
            right--;
            if (right < left) {
                break;
            }
            for (int col = right; col >= left; col--) {
                matrix[down][col] = ++c;
            }
            down--;
            if (down < up) {
                break;
            }
            for (int row = down; row >= up; row--) {
                matrix[row][left] = ++c;
            }
            left++;
            if (left > right) {
                break;
            }
        }
        return matrix;
    }
}