Added Island Perimeter

Author: ryanoneill

src/island_perimeter.rs

@@ -0,0 +1,81 @@
+/// You are given `row x col` `grid` representing a map where `grid[i][j] = 1` represents land and
+/// `grid[i][j] = 0` represents water.
+///
+/// Grid cells are connected horizontall/vertically (not diagonally). The `grid` is completely
+/// surrounded by water, and there is exactly one island (e.g., one or more connected land cells).
+///
+/// The island doesn't have "lakes", meaning the water inside 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.
+struct Solution;
+
+impl Solution {
+
+    pub fn island_perimeter(grid: Vec<Vec<i32>>) -> i32 {
+        let m = grid.len();
+        let n = grid[0].len();
+
+        let mut result = 0;
+
+        for i in 0..m {
+            for j in 0..n {
+                if grid[i][j] == 1 {
+                    // above
+                    let above = if i == 0 { 0 } else { grid[i-1][j] };
+
+                    // below
+                    let below = if i == m-1 { 0 } else { grid[i+1][j] };
+
+                    // left
+                    let left = if j == 0 { 0 } else { grid[i][j-1] };
+
+                    // right
+                    let right = if j == n-1 { 0 } else { grid[i][j+1] };
+
+                    let count = above + below + left + right;
+                    let sides = 4 - count;
+                    result += sides;
+                }
+            }
+        }
+
+        result
+    }
+
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    #[test]
+    fn example_1() {
+        let grid = vec![
+            vec![0,1,0,0],
+            vec![1,1,1,0],
+            vec![0,1,0,0],
+            vec![1,1,0,0],
+        ];
+        let result = Solution::island_perimeter(grid);
+        assert_eq!(result, 16);
+    }
+
+    #[test]
+    fn example_2() {
+        let grid = vec![
+            vec![1],
+        ];
+        let result = Solution::island_perimeter(grid);
+        assert_eq!(result, 4);
+    }
+
+    #[test]
+    fn example_3() {
+        let grid = vec![
+            vec![1, 0],
+        ];
+        let result = Solution::island_perimeter(grid);
+        assert_eq!(result, 4);
+    }
+
+}

src/lib.rs

@@ -414,6 +414,8 @@ pub mod repeated_substring_pattern; // 459 ✓
 
 pub mod hamming_distance; // 461 ✓
 
+pub mod island_perimeter; // 463
+
 pub mod ones_and_zeroes; // 474
 
 pub mod sliding_window_median; // 480 ✓