code.cpp

/* **************************************************************************
 * Copyright 2024 The OpenGenus.org Authors. All Rights Reserved.
 *
 * Code for the book "DAILY 43: Algorithmic Problems for Coding Interviews: Easy level, C++ edition"
 *
 * Licensed under the GNU General Public License, Version 3.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.gnu.org/licenses/gpl-3.0.html
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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 *
 * For details about the book, please visit: https://www.amazon.com/dp/B0CZJNBLQS
 * *************************************************************************/

#include <iostream>
#include <vector>

int islandPerimeter(std::vector<std::vector<int>>& grid) {
    int count = 0, repeat = 0;
    for(int i = 0; i < grid.size(); ++i) {
        for(int j = 0; j < grid[i].size(); ++j) {
            if(grid[i][j] == 1) {
                ++count;
                if(i != 0 && grid[i - 1][j] == 1) ++repeat;
                if(j != 0 && grid[i][j - 1] == 1) ++repeat;
            }
        }
    }
    return 4 * count - repeat * 2;
}

int main() {
    std::vector<std::vector<int>> grid = {{0, 1, 0, 0},
                                           {1, 1, 1, 0},
                                           {0, 1, 0, 0},
                                           {1, 1, 0, 0}};

    int perimeter = islandPerimeter(grid);
    std::cout << "Island perimeter: " << perimeter << std::endl;

    return 0;
}