#733. Flood Fill

最新推荐文章于 2022-06-30 21:34:12 发布

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最新推荐文章于 2022-06-30 21:34:12 发布

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分类专栏： leetcode 文章标签： java

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本文探讨了如何使用深度学习原理进行图像色彩填充，通过深度优先搜索（DFS）算法实现 floodFill 功能。从给定的二维网格图像出发，遇到相同颜色的相邻像素进行递归替换，直至整个区域都被新颜色覆盖。实例演示了如何在Java代码中操作像素并应用到实际问题中。

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Description

An image is represented by an m x n integer grid image where image[i][j] represents the pixel value of the image.

You are also given three integers sr, sc, and newColor. You should perform a flood fill on the image starting from the pixel image[sr][sc].

To perform a flood fill, consider the starting pixel, plus any pixels connected 4-directionally to the starting pixel of the same color as the starting pixel, plus any pixels connected 4-directionally to those pixels (also with the same color), and so on. Replace the color of all of the aforementioned pixels with newColor.

Return the modified image after performing the flood fill.

Examples

Example 1:
在这里插入图片描述

Input: image = [[1,1,1],[1,1,0],[1,0,1]], sr = 1, sc = 1, newColor = 2
Output: [[2,2,2],[2,2,0],[2,0,1]]
Explanation: From the center of the image with position (sr, sc) = (1, 1) (i.e., the red pixel), all pixels connected by a path of the same color as the starting pixel (i.e., the blue pixels) are colored with the new color.
Note the bottom corner is not colored 2, because it is not 4-directionally connected to the starting pixel.

Example 2:

Input: image = [[0,0,0],[0,0,0]], sr = 0, sc = 0, newColor = 2
Output: [[2,2,2],[2,2,2]]

Constraints:
m == image.length
n == image[i].length
1 <= m, n <= 50
0 <= image[i][j], newColor < 216
0 <= sr < m
0 <= sc < n

思路

就是dfs，但需要注意的是进入dfs前的判断条件，如果 oldColor == newColor，就不用往下继续了，否则会死循环

代码

class Solution {
    public int[][] changeColor(int[][] image, int i, int j, int newColor, int oldColor) {
        image[i][j] = newColor;
        
        if (j + 1 < image[0].length && image[i][j + 1] == oldColor)
            image = changeColor(image, i, j + 1, newColor, oldColor);
        if (j - 1 >= 0 && image[i][j - 1] == oldColor)
            image = changeColor(image, i, j - 1, newColor, oldColor);
        if (i + 1 < image.length && image[i + 1][j] == oldColor)
            image = changeColor(image, i + 1, j, newColor, oldColor);
        if (i - 1 >= 0 && image[i - 1][j] == oldColor)
            image = changeColor(image, i - 1, j, newColor, oldColor);
        
        return image;
    }
    public int[][] floodFill(int[][] image, int sr, int sc, int newColor) {
        if (newColor == image[sr][sc])
            return image;
        return changeColor(image, sr, sc, newColor, image[sr][sc]);
    }
}