go语言LeetCode题解1030距离顺序排列矩阵单元格

输入：rows = 1, cols = 2, rCenter = 0, cCenter = 0
输出：[[0,0],[0,1]]
解释：从 (r0, c0) 到其他单元格的距离为：[0,1]

输入：rows = 2, cols = 2, rCenter = 0, cCenter = 1
输出：[[0,1],[0,0],[1,1],[1,0]]
解释：从 (r0, c0) 到其他单元格的距离为：[0,1,1,2]
[[0,1],[1,1],[0,0],[1,0]] 也会被视作正确答案。

输入：rows = 2, cols = 3, rCenter = 1, cCenter = 2
输出：[[1,2],[0,2],[1,1],[0,1],[1,0],[0,0]]
解释：从 (r0, c0) 到其他单元格的距离为：[0,1,1,2,2,3]
其他满足题目要求的答案也会被视为正确，例如 [[1,2],[1,1],[0,2],[1,0],[0,1],[0,0]]。

class Solution {
     public  int[][] allCellsDistOrder(int R, int C, int r0, int c0) {
        int[][] a = new int[R * C][2];
        for (int i = 0; i < R; i++) {
            for (int j = 0; j < C; j++) {
                a[i * C + j] = new int[]{i, j};
            }
        }
        sort(a, 0, a.length - 1, r0, c0);
        return a;
    }
    private static void sort(int[][] a, int lo, int hi, int r0, int c0) {
        if (hi <= lo) {
            return;
        }
        int j = partition(a, lo, hi, r0, c0);
        sort(a, lo, j - 1, r0, c0);
        sort(a, j + 1, hi, r0, c0);
    }
 private static int partition(int[][] a, int lo, int hi, int r0, int c0) {
        int i = lo;
        int j = hi + 1;
        while (true) {
            while (less(a, ++i, lo, r0, c0)) {
                if (i >= hi) {
                    break;
                }
            }
            while (less(a, lo, --j, r0, c0)) {
                if (j <= lo) {
                    break;
                }
            }
            if (i >= j) {
                break;
            }
            swap(a, i, j);
        }
        swap(a, lo, j);
        return j;
    }
    private static void swap(int[][] a, int i, int j) {
        int[] tmp = a[i];
        a[i] = a[j];
        a[j] = tmp;
    }
    private static boolean less(int[][] a, int i, int j, int ro, int c0) {
        int[] arr1 = a[i];
        int[] arr2 = a[j];
        int len1 = Math.abs(arr1[0] - ro) + Math.abs(arr1[1] - c0);
        int len2 = Math.abs(arr2[0] - ro) + Math.abs(arr2[1] - c0);
        return len1 - len2 < 0;
    }
}