岛屿数量

题目描述

给一个01矩阵，1代表是陆地，0代表海洋， 如果两个1相邻，那么这两个1属于同一个岛。我们只考虑上下左右为相邻。
岛屿: 相邻陆地可以组成一个岛屿（相邻:上下左右） 判断岛屿个数。

示例1

输入

[[1,1,0,0,0],[0,1,0,1,1],[0,0,0,1,1],[0,0,0,0,0],[0,0,1,1,1]]

返回值

3

备注:

01矩阵范围<=200*200

题解

void dfs(int x, int y, vector<vector<char>> &grid, vector<vector<bool>> &mark, int height, int width) {
        if (x < 0 || y < 0 || x >= height || y >= width || mark[x][y] == false) {
            return;
        }
        if (grid[x][y] == '1') {
            mark[x][y] = false;
            dfs(x - 1, y, grid, mark, height, width);
            dfs(x + 1, y, grid, mark, height, width);
            dfs(x, y - 1, grid, mark, height, width);
            dfs(x, y + 1, grid, mark, height, width);
        }
    }
    /**
     * 判断岛屿数量
     * @param grid char字符型vector<vector<>> 
     * @return int整型
     */
    int solve(vector<vector<char> >& grid) {
        // write code here
        if (grid.size() == 0) {
            return 0;
        }
        int width = grid[0].size();
        int height = grid.size();
        int count = 0;
        vector<vector<bool>> mark(height, vector<bool>(width, true));
        for (int i = 0; i < height; ++i) {
            for (int j = 0; j < width; ++j) {
                if (grid[i][j] == '1' && mark[i][j] == true) {
                    dfs(i, j, grid, mark, height, width);
                    ++count;
                }
            }
        }
        return count;
    }