leetcode 463. 岛屿的周长(Island Perimeter)

目录

  • 题目描述:
  • 示例 :
  • 解法:

题目描述:

给定一个包含 0 和 1 的二维网格地图,其中 1 表示陆地 0 表示水域。

网格中的格子水平和垂直方向相连(对角线方向不相连)。整个网格被水完全包围,但其中恰好有一个岛屿(或者说,一个或多个表示陆地的格子相连组成的岛屿)。

岛屿中没有“湖”(“湖” 指水域在岛屿内部且不和岛屿周围的水相连)。格子是边长为 1 的正方形。网格为长方形,且宽度和高度均不超过 100 。计算这个岛屿的周长。

示例 :

输入:
    [[0,1,0,0],
     [1,1,1,0],
     [0,1,0,0],
     [1,1,0,0]]
输出:
    16

解释:
    它的周长是下面图片中的 16 个黄色的边:
    

解法:

class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        int m = grid.size();
        if(m == 0){
            return 0;
        }
        int n = grid[0].size();
        if(n == 0){
            return 0;
        }
        int res = 0;
        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(grid[i][j] == 1){
                    res += 4;
                    if(i > 0 && grid[i-1][j] == 1){
                        res -= 2;
                    }
                    if(j > 0 && grid[i][j-1] == 1){
                        res -= 2;
                    }
                }
            }
        }
        return res;
    }
};

原文地址:https://www.cnblogs.com/zhanzq/p/10593399.html

时间: 2024-10-08 16:00:52

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