js 解 岛屿的最大面积

function AreaMost(){
    this.area=1,       // 初始化，记录某个页面
    this.position=[]   // 存储当前岛屿点所在的坐标位置，是个二维数组。每个数组两个值，[x,y]
}
var gg=[[0,0,1,0,0,0,0,1,0,0,0,0,0],
        [0,0,0,0,0,0,0,1,1,1,0,0,0],
        [0,1,1,0,1,0,0,0,0,0,0,0,0],
        [0,1,0,0,1,1,0,0,1,0,1,0,0],
        [0,1,0,0,1,1,0,0,1,1,1,0,0],
        [0,0,0,0,0,0,0,0,0,0,1,0,0],
        [0,0,0,0,0,0,0,1,1,1,0,0,0],
        [0,0,0,0,0,0,0,1,1,0,0,0,0]];
var maxAreaOfIsland = function(grid) {
    var rel=[];
    for(var i=0;i<grid.length;i++){
        for(var j=0;j<grid[i].length;j++){
            if(grid[i][j]==1){
                 var aa=new AreaMost();
                 aa.position.push([i,j]);
                 grid[i][j]=0;
                 // 扩展当前区域
                 aa=expanding(i,j,aa,grid,true,true,true,true);
                 rel.push(aa);
            }
        }
    }
    var maxArea=0;
    for(var ind in rel){
       if(rel[ind].area>maxArea){
           maxArea=Number(rel[ind].area);
       }
    }
    return maxArea;
};
function expanding(x,y,target,grid,up,down,left,right){ // 先将area 递归寻找扩展
     if(up){                                 // 直接传 x,y。值传递是 复制，不会被修改       
        if(isValid(x-1,y,grid)&&grid[x-1][y]==1){   // 上  
            target.position.push([x-1,y]);
            target.area++;
            grid[x-1][y]=0;
            expanding(x-1,y,target,grid,true,false,true,true);
        }
     }
     if(down){
        if(isValid(x+1,y,grid)&&grid[x+1][y]==1){   // 下
            target.position.push([x+1,y]);
            target.area++;
            grid[x+1][y]=0;
            expanding(x+1,y,target,grid,false,true,true,true);
        }
     }
     if(left){
        if(isValid(x,y-1,grid)&&grid[x][y-1]==1){   // 左
            target.position.push([x,y-1]);
            target.area++;
            grid[x][y-1]=0;
            expanding(x,y-1,target,grid,true,true,true,false);
        }
     }
     if(right){
        if(isValid(x,y+1,grid)&&grid[x][y+1]==1){   //  右 
             target.position.push([x-1,y]);
             target.area++;
             grid[x][y+1]=0;
             expanding(x,y+1,target,grid,true,true,false,true);
        }
     } 
     return target;
}
function isValid(x,y,grid){
    if( 0<=x && x<grid.length && 0<=y && y<grid[0].length){    
        return true;
    }
    return false;
}
console.log(maxAreaOfIsland(gg));

本文地址：https://blog.csdn.net/qq_37786243/article/details/85951474