岛屿数量(Number of Islands)

给你一个由 '1'（陆地）和 '0'（水）组成的的二维网格，请你计算网格中岛屿的数量。

岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。

此外，你可以假设该网格的四条边均被水包围。

示例 1：

输入：grid = [
  ["1","1","1","1","0"],
  ["1","1","0","1","0"],
  ["1","1","0","0","0"],
  ["0","0","0","0","0"]
]
输出：1

示例 2：

输入：grid = [
  ["1","1","0","0","0"],
  ["1","1","0","0","0"],
  ["0","0","1","0","0"],
  ["0","0","0","1","1"]
]
输出：3

提示：

  • m == grid.length
  • n == grid[i].length
  • 1 <= m, n <= 300
  • grid[i][j] 的值为 '0' 或 '1'

我们找到一个岛屿之后就把他清零，当所有数字都为0时，就表示结束了

const char WATER = '0';
const char LAND = '1';
const char NEW = 'X';
const char USED = 'O';
void floodFill(char** grid,int NUMBER_OF_ROWS,int NUMBER_OF_COLS,int i,int j){

    if(i<0 || i>=NUMBER_OF_ROWS || j<0 || j>=NUMBER_OF_COLS||grid[i][j]!=LAND)return;
    grid[i][j] = NEW;
    floodFill(grid,NUMBER_OF_ROWS,NUMBER_OF_COLS,i-1,j);
    floodFill(grid,NUMBER_OF_ROWS,NUMBER_OF_COLS,i+1,j);
    floodFill(grid,NUMBER_OF_ROWS,NUMBER_OF_COLS,i,j-1);
    floodFill(grid,NUMBER_OF_ROWS,NUMBER_OF_COLS,i,j+1);
}

int numIslands(char** grid, int gridSize, int* gridColSize){
    if (gridSize == 0) return 0;
    char q = grid[0][0];
    const int NUMBER_OF_ROWS = gridSize;
    const int NUMBER_OF_COLS = gridColSize[0];

    int numberOfRegions = 0;
    for (int i =0;i<NUMBER_OF_ROWS;i++){
        for(int j =0;j<NUMBER_OF_COLS;j++){
            if(grid[i][j] == LAND){
                floodFill(grid,NUMBER_OF_ROWS,NUMBER_OF_COLS,i,j);
                for(int y =0;y<NUMBER_OF_ROWS;y++){
                    for(int x=0;x<NUMBER_OF_COLS;x++){
                        if(grid[y][x]==NEW) {
                            grid[y][x]=USED;
                        }
                    }
                }
                numberOfRegions++;
            }
        }
    }
    return numberOfRegions;
}