Leetcode 463. Island Perimeter 求岛的周长 解题报告

1 解题思想

这道题是说给了一个二位数字，代表一个棋盘地图，1代表岛屿占用的地方，其他地方为海

1一定会围成一个岛，那么求岛的周长。

这道题其实我是傻傻的遍历，然后看看当前可以加几条边就好了。。

2 原题

You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/vertically (not diagonally). The grid is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells). The island doesn’t have “lakes” (water inside that isn’t connected to the water around the island). One cell is a square with side length 1. The grid is rectangular, width and height don’t exceed 100. Determine the perimeter of the island.

Example:

[[0,1,0,0],

[1,1,1,0],

[0,1,0,0],

[1,1,0,0]]

Answer: 16

Explanation: The perimeter is the 16 yellow stripes in the image below:

3 AC解

public class Solution {
/**
* 直接傻傻的判断就好了 哈哈
* */
public int islandPerimeter(int[][] grid) {
int permeter = 0;
int n = grid.length;
int m = grid[0].length;
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
if(grid[i][j] == 1){
if(i==0 || grid[i-1][j] == 0) permeter++;
if(i==n-1 || grid[i+1][j] == 0) permeter++;
if(j==0 || grid[i][j-1] == 0) permeter++;
if(j==m-1 || grid[i][j+1] == 0) permeter++;
}
}
}
return permeter;
}
}