stashing changes

Author: bwaldrep

Primes.hs

@@ -0,0 +1,10 @@
+-- Project euler problems in Haskell
+
+module Primes where
+
+primes :: [Int]
+primes = 2 : 3 : 5 : filter isPrime [7..]
+    where isPrime :: Int -> Bool
+          isPrime n = 0 == ( length ( filter (\c -> gcd n c > 1) (candidates n) ) )
+          candidates :: Int -> [Int]
+          candidates n = takeWhile (< ((sqrt . fromIntegral) n)) primes

prob.py

@@ -0,0 +1,68 @@
+# Player A: 9 4-sided die
+# Player B: 6 6-sided die
+
+# compute the probability of the sum of player A's die
+# being higher than the sum of player B's die
+
+print (9**4) * (6**6)
+print (4**9) * (6**6)
+
+def compA():
+  A = [0 for k in range(36)]
+  for n in xrange(len(A)):
+    for a in xrange(1,5):
+      for b in xrange(1,5):
+        for c in xrange(1,5):
+          for d in xrange(1,5):
+            for e in xrange(1,5):
+              for f in xrange(1,5):
+                for g in xrange(1,5):
+                  for h in xrange(1,5):
+                    val = n + 1 - a - b - c - d - e - f - g - h
+                    if (val > 0) and (val < 5):
+                      A[n] += 1
+  return A
+
+A = compA()
+s = float(sum(A))
+for i, item in enumerate(A):
+	A[i] = item / s
+
+def compB():
+  B = [0 for k in range(36)]
+  for n in xrange(len(A)):
+    for a in xrange(1,7):
+      for b in xrange(1,7):
+        for c in xrange(1,7):
+          for d in xrange(1,7):
+            for e in xrange(1,7):
+              val = n + 1 - a - b - c - d - e
+              if (val > 0) and (val < 7):
+              	B[n] += 1
+  return B
+
+B = compB()
+s = float(sum(B))
+for i, item in enumerate(B):
+  B[i] = item / s
+
+# compute answer
+
+a = 0.0
+for i in range(36):
+  for j in range(i):
+  	a += A[i] * B[j]
+print a
+
+b = 0.0
+for i in range(36):
+  for j in range(i):
+  	b += A[j] * B[i]
+print b
+
+t = 0.0
+for i in range(36):
+  t += A[i] * B[i]
+print t
+
+print a + b + t

problem3.cpp

@@ -0,0 +1,84 @@
+#include <iostream>
+#include <stdio.h>
+#include <cmath>
+#include <vector>
+#include <map>
+
+using namespace std;
+
+typedef long long int lli;
+typedef long int li;
+typedef vector<bool> table;
+
+lli compFactor(lli num);
+void buildTable(lli cap, table &lookup);
+lli firstFactor(lli num);
+
+int main() {
+
+  lli bignum = 600851475143;
+
+  cout << "ANSWER: " << compFactor(bignum) << endl;
+  return 0;
+}
+
+lli compFactor(lli num) {
+  lli prev, ans, current;
+  current = num;
+  prev = ans = 1;
+  while(true) {
+    prev = ans;
+    ans = firstFactor(current);
+    if(!ans) {
+      break;
+    }
+    current = current / ans;
+//    printf("num: %lld  current: %lld  ans: %lld  prev: %lld\n", num, current, ans, prev);
+  }
+
+  return current;
+}
+
+
+lli firstFactor(lli num) {
+  table lookup;
+  buildTable(sqrt(num),lookup);
+  lli size = lookup.size();
+  for(lli i = 3; i < size; i += 2) {
+    if(lookup[i] && (num % i == 0)) {
+      return i;
+    }
+  }
+  return 0;
+}
+
+void buildTable(lli cap, table &lookup) {
+  lookup.resize(cap);
+  lookup[0] = lookup[1] = false;
+  for(lli i = 2; i < cap; i++) {
+      lookup[i] = true;
+  }
+  for(lli i = 2; i < cap; i++) {
+      if (lookup[i]) {
+        for(lli j = 2 * i; j < cap; j += i) {
+            lookup[j] = false;
+        }
+      }
+  }
+  return;
+}
+
+bool isPrime(lli num, table lookup) {
+  lli size = lookup.size();
+  if (num < size) {
+    return lookup[num];
+  }
+
+  lli stop = sqrt(num);
+  for(lli i = 3; i < stop; i += 2) {
+      if (lookup[i] && (num % i == 0)) {
+         return false;
+      }
+  }
+  return true;
+}