number of islands problem solved

.gitignore

@@ -3,6 +3,7 @@
 debug/
 target/
 hands-on_01/
+hands-on_02/
 
 # Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
 # More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html

2023_11_30/x-total-shapes/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "x-total-shapes"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2023_11_30/x-total-shapes/src/main.rs

@@ -0,0 +1,65 @@
+struct Solution;
+
+impl Solution {
+    pub fn dfs(grid: &mut Vec<Vec<char>>, i: usize, j: usize) {
+        let rows = grid.len();
+        let cols = grid[0].len();
+
+        if i >= rows || j >= cols || grid[i][j] == '0' {
+            return;
+        }
+
+        grid[i][j] = '0';
+
+        if i > 0 { Self::dfs(grid, i - 1, j); }
+        if j > 0 { Self::dfs(grid, i, j - 1); }
+        Self::dfs(grid, i + 1, j);
+        Self::dfs(grid, i, j + 1);
+    }
+
+    pub fn num_islands(grid: &mut Vec<Vec<char>>) -> i32 {
+         let mut count = 0;
+         let rows = grid.len();
+         let cols = grid[0].len();
+
+         for i in 0..rows {
+             for j in 0..cols {
+                 if grid[i][j] == '1' {
+                     Self::dfs(grid, i, j);
+                     count += 1;
+                 }
+             }
+         }
+         count
+     }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test1() {
+        let mut grid1 = vec![
+            vec!['1', '1', '1', '1', '0'],
+            vec!['1', '1', '0', '1', '0'],
+            vec!['1', '1', '0', '0', '0'],
+            vec!['0', '0', '0', '0', '0'],
+        ];
+        assert_eq!(Solution::num_islands(&mut grid1), 1);
+    }
+
+    #[test]
+    fn test2() {
+        let mut grid2 = vec![
+            vec!['1', '1', '0', '0', '0'],
+            vec!['1', '1', '0', '0', '0'],
+            vec!['0', '0', '1', '0', '0'],
+            vec!['0', '0', '0', '1', '1'],
+        ];
+        assert_eq!(Solution::num_islands(&mut grid2), 3);
+    }
+}
+
+fn main() {
+}