Data update

Task/Partition-function-P/Rust/partition-function-p.rs

@@ -0,0 +1,46 @@
+// [dependencies]
+// rug = "1.11"
+
+use rug::Integer;
+
+fn partitions(n: usize) -> Integer {
+    let mut p = Vec::with_capacity(n + 1);
+    p.push(Integer::from(1));
+    for i in 1..=n {
+        let mut num = Integer::from(0);
+        let mut k = 1;
+        loop {
+            let mut j = (k * (3 * k - 1)) / 2;
+            if j > i {
+                break;
+            }
+            if (k & 1) == 1 {
+                num += &p[i - j];
+            } else {
+                num -= &p[i - j];
+            }
+            j += k;
+            if j > i {
+                break;
+            }
+            if (k & 1) == 1 {
+                num += &p[i - j];
+            } else {
+                num -= &p[i - j];
+            }
+            k += 1;
+        }
+        p.push(num);
+    }
+    p[n].clone()
+}
+
+fn main() {
+    use std::time::Instant;
+    let n = 6666;
+    let now = Instant::now();
+    let result = partitions(n);
+    let time = now.elapsed();
+    println!("P({}) = {}", n, result);
+    println!("elapsed time: {} microseconds", time.as_micros());
+}