LeetCode -- 保持城市天际线

在二维数组grid中,grid[i][j]代表位于某处的建筑物的高度。 我们被允许增加任何数量(不同建筑物的数量可能不同)的建筑物的高度。 高度 0 也被认为是建筑物。

最后,从新数组的所有四个方向(即顶部,底部,左侧和右侧)观看的“天际线”必须与原始数组的天际线相同。 城市的天际线是从远处观看时,由所有建筑物形成的矩形的外部轮廓。 请看下面的例子。

建筑物高度可以增加的最大总和是多少?

例子:

输入: grid = [[3,0,8,4],[2,4,5,7],[9,2,6,3],[0,3,1,0]]
输出: 35

解释:
The grid is:

[ [3, 0, 8, 4],
[2, 4, 5, 7],
[9, 2, 6, 3],
[0, 3, 1, 0] ]

从数组竖直方向(即顶部,底部)看“天际线”是:[9, 4, 8, 7]
从水平水平方向(即左侧,右侧)看“天际线”是:[8, 7, 9, 3]

在不影响天际线的情况下对建筑物进行增高后,新数组如下:

gridNew = [ [8, 4, 8, 7],
[7, 4, 7, 7],
[9, 4, 8, 7],
[3, 3, 3, 3] ]

说明:

1 < grid.length = grid[0].length <= 50。
grid[i][j] 的高度范围是: [0, 100]。
一座建筑物占据一个grid[i][j]:换言之,它们是 1 x 1 x grid[i][j] 的长方体。

public class maxIncreaseKeepingSkyline {

    @Test
    public void maxIncreaseKeepingSkylineTest() {
        int[][] gird = new int[][]
                {
                        {3, 0, 8, 4},
                        {2, 4, 5, 7},
                        {9, 2, 6, 3},
                        {0, 3, 1, 0}
                };
        Assert.assertEquals(35, maxIncreaseKeepingSkyline(gird));
    }

    @Test
    public void getSkyLineTransversalTest() {
        int[][] gird = new int[][]
                {
                        {3, 0, 8, 4},
                        {2, 4, 5, 7},
                        {9, 2, 6, 3},
                        {0, 3, 1, 0}
                };
        Assert.assertArrayEquals(new int[] {9, 4, 8, 7}, getSkyLineTransversal(gird));
    }

    @Test
    public void getSkyLineVerticalTest() {
        int[][] gird = new int[][]
                {
                        {3, 0, 8, 4},
                        {2, 4, 5, 7},
                        {9, 2, 6, 3},
                        {0, 3, 1, 0}
                };
        Assert.assertArrayEquals(new int[] {8, 7, 9, 3}, getSkyLineVertical(gird));
    }


    public int maxIncreaseKeepingSkyline(int[][] grid) {
        int[] skyLineT = getSkyLineTransversal(grid);
        int[] skyLineV = getSkyLineVertical(grid);
        int tLength = grid.length;
        int vLength = grid[0].length;
        int sum = 0;
        for (int i = 0; i < tLength; i++) {
            for (int j = 0; j < vLength; j++) {
                sum += (getMin(skyLineT[j], skyLineV[i]) - grid[i][j]);
            }
        }
        return sum;
    }

    private int getMin(int i, int i1) {
        return i < i1 ? i : i1;
    }

    public int[] getSkyLineTransversal(int[][] grid) {
        int[] skyLineTransversal = new int[grid.length];
        int bound = grid.length;
         for (int i = 0; i < bound; i++) {
            int boundT = grid[0].length;
            int temp[] = new int[boundT];
            for (int j = 0; j < boundT; j++) {
                temp[j]= grid[j][i];
            }
             skyLineTransversal[i] = Arrays.stream(temp).max().getAsInt();
        }

        return skyLineTransversal;
    }

    public int[] getSkyLineVertical(int[][] grid) {
        int[] skyLineVertical = new int[grid[0].length];
        int bound = grid.length;
        for (int i = 0; i < bound; i++) {
            skyLineVertical[i] = Arrays.stream(grid[i]).max().getAsInt();
        }

        return skyLineVertical;
    }
}

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转载自blog.csdn.net/ydonghao2/article/details/80248488