leetcode_200

岛屿数量

分析：对于一个1来说，结果+1，并将它和与它联通的所有1翻转为0，循环一次返回结果

var numIslands = function (grid) {
    let num = 0
    if(grid.length && grid[0].length) {
        let rows = grid.length-1
        let colums = grid[0].length-1
        function over(i, j) {
            if(i<0 || j<0 || i>rows || j>colums) return
            if(grid[i][j]=='1') {
                grid[i][j] = 0
                over(i-1,j)
                over(i,j-1)
                over(i+1,j)
                over(i,j+1)
            }
        }
        for(let i=0; i<rows; i++) {
            for(let j=0; j<colums; j++){
                if(grid[i][j]=='1'){
                    num++
                    over(i, j)
                }
            }
        }
        return num
    }
}