Leetcode 463. Island Perimeter

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        int perimeter = 0;
        int rows = grid.size();
        int columns = grid[0].size();
        for(int i = 0; i < rows; i++) {
            for(int j = 0; j < columns; j++) {
                if(grid[i][j]) {
                    getPerimeter(grid, i, j, perimeter, rows, columns);
                    return perimeter;
                }
            }
        }
    }
private:
    void getPerimeter(vector<vector<int>>& grid, int i, int j, int& perimeter, int& rows, int& columns) {
        if(i < 0 || i == rows || j < 0 || j == columns || grid[i][j] == 0) {
            perimeter++;
            return;
        }
        if(grid[i][j] == -1) {
            return;
        }
        grid[i][j] = -1;
        getPerimeter(grid, i + 1, j, perimeter, rows, columns);
        getPerimeter(grid, i - 1, j, perimeter, rows, columns);
        getPerimeter(grid, i, j + 1, perimeter, rows, columns);
        getPerimeter(grid, i, j - 1, perimeter, rows, columns);
    }
};

Reference

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