ugh, finally works

.gitignore

@@ -0,0 +1 @@
+*/target/

happy_number/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "happy_number"
+version = "0.1.0"

happy_number/Cargo.toml

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+[package]
+name = "happy_number"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

happy_number/src/main.rs

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+struct Solution {}
+
+impl Solution {
+    pub fn is_happy(n: i32) -> bool {
+        let mut s = std::collections::HashSet::new();
+        let mut n = n;
+        while s.insert(n) {
+            n = Self::sum_squares(n);
+        }
+        n == 1
+    }
+
+    fn sum_squares(n: i32) -> i32 {
+        n.to_string()
+            .chars()
+            .map(|c| c.to_digit(10).unwrap_or(0).pow(2))
+            .sum::<u32>() as i32
+    }
+}
+
+fn main() {
+    println!("{}", Solution::is_happy(19));
+}

spiral_matrix/Cargo.toml

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+[package]
+name = "spiral_matrix"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

spiral_matrix/src/main.rs

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+struct Solution();
+
+impl Solution {
+    pub fn spiral_order(matrix: &[&[i32]]) -> Vec<i32> {
+        let mut fr = 0;
+        let mut lr = matrix.len() - 1;
+        let mut fc = 0;
+        let mut lc = matrix.get(0).unwrap().len() - 1;
+        let mut spiral = Vec::with_capacity((lr + 1) * (lc + 1));
+        let cols = lc + 1;
+        let size = matrix.len() * cols;
+        loop {
+            dbg!(fr, lr, fc, lc);
+            // right
+            for i in fc..=lc {
+                spiral.push(matrix[fr][i]);
+            }
+            fr += 1;
+            if spiral.len() == size {}
+
+            // down
+            for row in fr..=lr {
+                spiral.push(matrix[row][lc]);
+            }
+            lc = lc.saturating_sub(1);
+            if spiral.len() == size {
+                break;
+            }
+
+            // left
+            if fr <= lr {
+                for e in (fc..=lc).rev() {
+                    spiral.push(matrix[lr][e]);
+                }
+            }
+            lr = lr.saturating_sub(1);
+            if spiral.len() == size {
+                break;
+            }
+
+            // up
+            if fc <= lc {
+                for i in (fr..=lr).rev() {
+                    spiral.push(matrix[i][fc]);
+                }
+            }
+            fc += 1;
+            if spiral.len() == size {
+                break;
+            }
+
+            dbg!(&spiral);
+        }
+
+        spiral
+    }
+}
+
+fn main() {
+    dbg!(Solution::spiral_order(&[
+        &[1, 2, 3],
+        &[4, 5, 6],
+        &[7, 8, 9]
+    ]));
+
+    dbg!(Solution::spiral_order(&[&[3], &[2]]));
+}