Data commit

Task/Brilliant-numbers/Go/brilliant-numbers.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "rcu"
+    "sort"
+)
+
+var primes = rcu.Primes(1e8 - 1)
+
+type res struct {
+    bc   interface{}
+    next int
+}
+
+func getBrilliant(digits, limit int, countOnly bool) res {
+    var brilliant []int
+    count := 0
+    pow := 1
+    next := math.MaxInt
+    for k := 1; k <= digits; k++ {
+        var s []int
+        for _, p := range primes {
+            if p >= pow*10 {
+                break
+            }
+            if p > pow {
+                s = append(s, p)
+            }
+        }
+        for i := 0; i < len(s); i++ {
+            for j := i; j < len(s); j++ {
+                prod := s[i] * s[j]
+                if prod < limit {
+                    if countOnly {
+                        count++
+                    } else {
+                        brilliant = append(brilliant, prod)
+                    }
+                } else {
+                    if next > prod {
+                        next = prod
+                    }
+                    break
+                }
+            }
+        }
+        pow *= 10
+    }
+    if countOnly {
+        return res{count, next}
+    }
+    return res{brilliant, next}
+}
+
+func main() {
+    fmt.Println("First 100 brilliant numbers:")
+    brilliant := getBrilliant(2, 10000, false).bc.([]int)
+    sort.Ints(brilliant)
+    brilliant = brilliant[0:100]
+    for i := 0; i < len(brilliant); i++ {
+        fmt.Printf("%4d ", brilliant[i])
+        if (i+1)%10 == 0 {
+            fmt.Println()
+        }
+    }
+    fmt.Println()
+    for k := 1; k <= 13; k++ {
+        limit := int(math.Pow(10, float64(k)))
+        r := getBrilliant(k, limit, true)
+        total := r.bc.(int)
+        next := r.next
+        climit := rcu.Commatize(limit)
+        ctotal := rcu.Commatize(total + 1)
+        cnext := rcu.Commatize(next)
+        fmt.Printf("First >= %18s is %14s in the series: %18s\n", climit, ctotal, cnext)
+    }
+}