src/bin/perfect-squares.rs

Author: bestgopher

src/bin/perfect-squares.rs

@@ -0,0 +1,40 @@
+fn main() {
+    println!("{}", Solution::num_squares(12));
+    println!("{}", Solution::num_squares(13));
+}
+
+struct Solution;
+
+impl Solution {
+    pub fn num_squares(n: i32) -> i32 {
+        let mut h = std::collections::HashMap::new();
+        Self::f(n, &mut h)
+    }
+
+    fn f(n: i32, h: &mut std::collections::HashMap<i32, i32>) -> i32 {
+        if n == 0 {
+            return 0;
+        }
+
+        if let Some(&x) = h.get(&n) {
+            return x;
+        }
+
+        let mut s = 0;
+
+        let mut m = 1;
+        while m * m <= n {
+            let s1 = 1 + Self::f(n - m * m, h);
+            if s == 0 {
+                s = s1;
+            } else {
+                s = s.min(s1)
+            }
+            m += 1;
+        }
+
+        h.insert(n, s);
+
+        s
+    }
+}