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Island Perimeter

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Description

https://leetcode.com/problems/island-perimeter/

Solution

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class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        vector<vector<int>> dir = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};
        int height = grid.size();
        if (height == 0) return 0;
        
        int width = grid[0].size();
        int ret = 0;
        for (int i = 0; i < grid.size(); ++i) {
            for (int j = 0; j < grid[0].size(); ++j) {
                if (grid[i][j] == 0) continue;
                for (int k = 0; k < 4; ++k) {
                    int newX = dir[k][0] + i;
                    int newY = dir[k][1] + j;
                    if (newX < 0 || newX >= height 
                        || newY < 0 || newY >= width 
                            || grid[newX][newY] == 0) {
                        ret += 1;
                    }
                }
            }
        }
        return ret;
    }
};