Add tasks for all the new languages

Task/Unbias-a-random-generator/ERRE/unbias-a-random-generator.erre

@@ -0,0 +1,30 @@
+PROGRAM UNBIAS
+
+FUNCTION RANDN(N)
+   RANDN=INT(1+N*RND(1))=1
+END FUNCTION
+
+PROCEDURE UNBIASED(N->RIS)
+      LOCAL A,B
+      REPEAT
+        A=RANDN(N)
+        B=RANDN(N)
+      UNTIL A<>B
+      RIS=A
+END PROCEDURE
+
+BEGIN
+  PRINT(CHR$(12);) ! CLS
+  RANDOMIZE(TIMER)
+
+  FOR N=3 TO 6 DO
+        BIASED=0
+        UNBIASED=0
+        FOR I=1 TO 10000 DO
+          IF RANDN(N) THEN biased+=1
+          UNBIASED(N->RIS)
+          IF RIS THEN unbiased+=+1
+        END FOR
+        PRINT("N =";N;" : biased =";biased/100;", unbiased =";unbiased/100)
+  END FOR
+END PROGRAM

Task/Unbias-a-random-generator/Nim/unbias-a-random-generator.nim

@@ -0,0 +1,38 @@
+import math, strutils
+randomize()
+
+template newSeqWith(len: int, init: expr): expr =
+  var result {.gensym.} = newSeq[type(init)](len)
+  for i in 0 .. <len:
+    result[i] = init
+  result
+
+proc randN(n): (proc: range[0..1]) =
+  result = proc(): range[0..1] =
+    if random(n) == 0: 1 else: 0
+
+proc unbiased(biased): range[0..1] =
+  var (this, that) = (biased(), biased())
+  while this == that:
+    this = biased()
+    that = biased()
+  return this
+
+for n in 3..6:
+  var biased = randN(n)
+  var v = newSeqWith(1_000_000, biased())
+  var cnt0, cnt1 = 0
+  for x in v:
+    if x == 0: inc cnt0
+    else:      inc cnt1
+  echo "Biased(",n,")  = count1=",cnt1,", count0=",cnt0,", percent=",
+       formatFloat(100 * float(cnt1)/float(cnt1+cnt0), ffDecimal, 3)
+
+  v = newSeqWith(1_000_000, unbiased(biased))
+  cnt0 = 0
+  cnt1 = 0
+  for x in v:
+    if x == 0: inc cnt0
+    else:      inc cnt1
+  echo "  Unbiased = count1=",cnt1,", count0=",cnt0,", percent=",
+       formatFloat(100 * float(cnt1)/float(cnt1+cnt0), ffDecimal, 3)

Task/Unbias-a-random-generator/Phix/unbias-a-random-generator.phix

@@ -0,0 +1,25 @@
+function randN(integer N)
+    return rand(N) = 1
+end function
+
+function unbiased(integer N)
+integer a
+    while 1 do
+        a = randN(N)
+        if a!=randN(N) then
+            return a
+        end if
+    end while
+end function
+
+constant n = 10000
+integer cb, cu
+for b=3 to 6 do
+    cb = 0
+    cu = 0
+    for i=1 to n do
+        cb += randN(b)
+        cu += unbiased(b)
+    end for
+    printf(1, "%d: %5.2f%%  %5.2f%%\n", {b, 100 * cb / n, 100 * cu / n})
+end for

Task/Unbias-a-random-generator/Ring/unbias-a-random-generator.ring

@@ -0,0 +1,19 @@
+for n = 3 to 6
+    biased = 0
+    unb = 0
+    for i = 1 to 10000
+        biased += randN(n)
+        unb += unbiased(n)
+    next
+    see "N = " + n + " : biased = " + biased/100  + "%, unbiased = " + unb/100 + "%" + nl
+next
+
+func unbiased nr
+     while 1
+           a = randN(nr)
+           if a != randN(nr) return a ok
+     end
+
+func randN m
+     m = (random(m) = 1)
+     return m

Task/Unbias-a-random-generator/Sidef/unbias-a-random-generator.sidef

@@ -0,0 +1,22 @@
+func randN (n) {
+    n.rand / (n-1) -> int
+}
+
+func unbiased(n) {
+    var n1 = nil
+    do { n1 = randN(n) } while (n1 == randN(n))
+    return n1
+}
+
+var iterations = 1000
+
+for n in (3..6) {
+    var raw = []
+    var fixed = []
+    iterations.times {
+          raw[    randN(n) ] := 0 ++
+        fixed[ unbiased(n) ] := 0 ++
+    }
+    printf("N=%d   randN: %s, %4.1f%%   unbiased: %s, %4.1f%%\n",
+        n, [raw, fixed].map {|a| (a.dump, a[1] * 100 / iterations) }...)
+}