init

problems/p28/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "p28"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

problems/p28/src/main.rs

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+// 1, 3, 5, 7, 9, 13, 17, 21, 25, 31
+//+2,+2,+2,+2,+4,+4,+4,+4, +6
+//
+//右上角固定为平方数，nxn
+
+fn main() {
+    let mut sum = 1;
+
+    let n = 1001;
+    for round in 1..=(n / 2) {
+        let base = (round * 2 + 1) * (round * 2 + 1);
+        sum += base * 4;
+        sum -= round * 2 * 6;
+    }
+    println!("{sum}");
+}