leetcode200岛屿的数量-蒲公英云

leetcode200岛屿的数量

在这里插入图片描述

思路：

遇到岛屿为1的时候递归访问其上下左右相邻的路径，递归完后岛屿数量++；
c语言里leetcode和实际使用是不一样的

代码leetcode，**类型指针直接用

void bfs(char** grid, int h,int w, int high,int width){ 
    if(h>=high||w>=width||h<0||w<0){ 
        return ;
    }
    else{ 
        if(grid[h][w]=='1'){ 
            grid[h][w] = '0';
            bfs(grid,h+1,w,high,width);
            bfs(grid,h-1,w,high,width);
            bfs(grid,h,w+1,high,width);
            bfs(grid,h,w-1,high,width);
        }
    }
}
int numIslands(char** grid, int gridSize, int* gridColSize){ 
    int i,j;
    int result = 0;
    for(i=0;i<gridSize;i++){ 
        for(j=0;j<*gridColSize;j++){ 
            if(grid[i][j]=='1'){ 
                bfs(grid,i,j,gridSize,*gridColSize);
                result++;
            }
        }
    }
    return result;
}

实际的二维数组访问

#include<stdio.h>
#include<string.h>
void bfs(char** grid, int h,int w, int high,int width){ 
    if(h>=high||w>=width||h<0||w<0){ 
        return ;
    }
    else{ 
        if(*((char*)grid+h*width+w)=='1'){ 
            printf("bfs grid[%d][%d]=%c\n",h,w,*((char*)grid+h*width+w));
            *((char*)grid+h*width+w) = '0';
            bfs(grid,h+1,w,high,width);
            bfs(grid,h-1,w,high,width);
            bfs(grid,h,w+1,high,width);
            bfs(grid,h,w-1,high,width);
        }
    }
}
int numIslands(char** grid, int gridSize, int* gridColSize){ 
    int i,j;
    int result = 0;
    printf("gridSize=%d ,gridColSize=%d\n",gridSize,* gridColSize);
    for(i=0;i<gridSize;i++){ 
        for(j=0;j<*gridColSize;j++){ 
            printf("grid[%d][%d]=%c\n",i,j,*((char*)grid+i*(* gridColSize)+j));
            if(*((char*)grid+i*(* gridColSize)+j)=='1'){ 
                bfs(grid,i,j,gridSize,*gridColSize);
                result++;
            }
        }
    }
    return result;
}
int main(){ 
    char grid[4][5] ={ { '1','1','1','1','0'},
                      { '1','1','0','1','0'},
                      { '1','1','0','0','0'},
                      { '0','0','0','0','0'}};
    int len = 5,i,j;
    int *p = &len;
    int r = 0;
    for (i = 0; i<4; i++) { 
    for (j = 0; j<5; j++) { 
            printf("%c ",*((char*)grid+i*5+j)); //通过线性计算
        }
        printf("\n");
    }
    r = numIslands((char **)grid,4,p);
    printf("result = %d\n",r);
    return 0;        
}