Data commit

Task/Earliest-difference-between-prime-gaps/Rust/earliest-difference-between-prime-gaps.rust

@@ -0,0 +1,55 @@
+// [dependencies]
+// primal = "0.3"
+
+fn main() {
+    use std::collections::HashMap;
+
+    let mut primes = primal::Primes::all();
+    let mut last_prime = primes.next().unwrap();
+    let mut gap_starts = HashMap::new();
+
+    let mut find_gap_start = move |gap: usize| -> usize {
+        if let Some(start) = gap_starts.get(&gap) {
+            return *start;
+        }
+        loop {
+            let prev = last_prime;
+            last_prime = primes.next().unwrap();
+            let diff = last_prime - prev;
+            if !gap_starts.contains_key(&diff) {
+                gap_starts.insert(diff, prev);
+            }
+            if gap == diff {
+                return prev;
+            }
+        }
+    };
+
+    let limit = 100000000000;
+
+    let mut pm = 10;
+    let mut gap1 = 2;
+    loop {
+        let start1 = find_gap_start(gap1);
+        let gap2 = gap1 + 2;
+        let start2 = find_gap_start(gap2);
+        let diff = if start2 > start1 {
+            start2 - start1
+        } else {
+            start1 - start2
+        };
+        if diff > pm {
+            println!(
+                "Earliest difference > {} between adjacent prime gap starting primes:\n\
+                Gap {} starts at {}, gap {} starts at {}, difference is {}.\n",
+                pm, gap1, start1, gap2, start2, diff
+            );
+            if pm == limit {
+                break;
+            }
+            pm *= 10;
+        } else {
+            gap1 = gap2;
+        }
+    }
+}