leetcode剑指 Offer II 105. 岛屿的最大面积

思路

1. 广度优先遍历，跟岛屿的数量一致

代码

#include<stdio.h>
#define max(a,b) ((a)>(b)?a:b)
int  max_area(int gridSize, int gridColSize,int **grid,int hang,int lie ){
    if(hang<0||hang>=gridSize||lie<0||lie>=gridColSize){
        printf("1\n");
        return 0;
    }
        
    if(*((int*)grid+hang*gridColSize+lie)==0)
        return 0;
    if(*((int*)grid+hang*gridColSize+lie)==1){
        *((int*)grid+hang*gridColSize+lie)=0;
        printf("hang = %d lie = %d\n",hang,lie);
        int t1=max_area(gridSize, gridColSize,grid,hang+1,lie);
        int t2=max_area(gridSize, gridColSize,grid,hang-1,lie);
        int t3=max_area(gridSize, gridColSize,grid,hang,lie+1);
        int t4=max_area(gridSize, gridColSize,grid,hang,lie-1);
        printf("t1=%d t2=%d t3=%d t4=%d\n",t1,t2,t3,t4);
        return (1+t1+t2+t3+t4);
    }
}


int maxAreaOfIsland(int gridSize, int gridColSize,int **grid){
    int maxarea = 0;
    int i =0,j=0; 
    for(i=0;i<gridSize;i++){
        for(j=0;j<gridColSize;j++){
            if(*((int*)grid+i*j+j)==1){
                int val = max_area(gridSize,gridColSize,grid,i,j);
                maxarea = max(maxarea,val);
            }
        }
    }
    return maxarea;
    
}
int main(){
    int grid[2][2]={{1,0},{1,0}};
    int gs = 2;
    int gcs = 2;
    int i,j;
    for(i=0;i<2;i++){
        for(j=0;j<2;j++){
            printf("%d ",grid[i][j]);
        }
        printf("\n");
    }
    int res = maxAreaOfIsland(gs,gcs,(int **)grid);

    for(i=0;i<2;i++){
        for(j=0;j<2;j++){
            printf("%d ",grid[i][j]);
        }
        printf("\n");
    }
    printf("res = %d\n",res);
    return 0;
}

leetcode

#define max(a,b) ((a)>(b)?a:b)
int  max_area(int gridSize, int gridColSize,int **grid,int hang,int lie ){
    if(hang<0||hang>=gridSize||lie<0||lie>=gridColSize){
        //printf("1\n");
        return 0;
    }
        
    if(grid[hang][lie]==0)
        return 0;
    if(grid[hang][lie]==1){
        grid[hang][lie]=0;
        //printf("hang = %d lie = %d\n",hang,lie);
        int t1=max_area(gridSize, gridColSize,grid,hang+1,lie);
        int t2=max_area(gridSize, gridColSize,grid,hang-1,lie);
        int t3=max_area(gridSize, gridColSize,grid,hang,lie+1);
        int t4=max_area(gridSize, gridColSize,grid,hang,lie-1);
        //printf("t1=%d t2=%d t3=%d t4=%d\n",t1,t2,t3,t4);
        return (1+t1+t2+t3+t4);
    }
    return  0;
}
int maxAreaOfIsland(int** grid, int gridSize, int* gridColSize){
    int maxarea = 0;
    int i =0,j=0; 
    //printf("csize = %d\n",*gridColSize);
    for(i=0;i<gridSize;i++){
        for(j=0;j<*gridColSize;j++){
            if(grid[i][j]==1){
                int val = max_area(gridSize,*gridColSize,grid,i,j);
                maxarea = max(maxarea,val);
            }
        }
    }
    return maxarea;
}