Move Project Euler under puzzles.

puzzles/project_euler/p008_LargestProductInASeries.cpp

@@ -0,0 +1,89 @@
+/* Check cf5-opt.vim defs.
+VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
+VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
+*/
+#include <iostream>
+
+/*
+Largest product in a series
+Problem 8
+
+Find the greatest product of five consecutive digits in the 1000-digit number.
+
+73167176531330624919225119674426574742355349194934
+96983520312774506326239578318016984801869478851843
+85861560789112949495459501737958331952853208805511
+12540698747158523863050715693290963295227443043557
+66896648950445244523161731856403098711121722383113
+62229893423380308135336276614282806444486645238749
+30358907296290491560440772390713810515859307960866
+70172427121883998797908792274921901699720888093776
+65727333001053367881220235421809751254540594752243
+52584907711670556013604839586446706324415722155397
+53697817977846174064955149290862569321978468622482
+83972241375657056057490261407972968652414535100474
+82166370484403199890008895243450658541227588666881
+16427171479924442928230863465674813919123162824586
+17866458359124566529476545682848912883142607690042
+24219022671055626321111109370544217506941658960408
+07198403850962455444362981230987879927244284909188
+84580156166097919133875499200524063689912560717606
+05886116467109405077541002256983155200055935729725
+71636269561882670428252483600823257530420752963450
+
+Solution:
+40824
+*/
+
+inline int d( char ch )
+{
+	return ch-'0';
+}
+
+int main ( void )
+{
+	const char * p =
+"73167176531330624919225119674426574742355349194934"
+"96983520312774506326239578318016984801869478851843"
+"85861560789112949495459501737958331952853208805511"
+"12540698747158523863050715693290963295227443043557"
+"66896648950445244523161731856403098711121722383113"
+"62229893423380308135336276614282806444486645238749"
+"30358907296290491560440772390713810515859307960866"
+"70172427121883998797908792274921901699720888093776"
+"65727333001053367881220235421809751254540594752243"
+"52584907711670556013604839586446706324415722155397"
+"53697817977846174064955149290862569321978468622482"
+"83972241375657056057490261407972968652414535100474"
+"82166370484403199890008895243450658541227588666881"
+"16427171479924442928230863465674813919123162824586"
+"17866458359124566529476545682848912883142607690042"
+"24219022671055626321111109370544217506941658960408"
+"07198403850962455444362981230987879927244284909188"
+"84580156166097919133875499200524063689912560717606"
+"05886116467109405077541002256983155200055935729725"
+"71636269561882670428252483600823257530420752963450";
+
+	const char * i = p;
+	const char * j = p+5;
+	int k = d(i[0])*d(i[1])*d(i[2])*d(i[3])*d(i[4]); // note there are no zeros  here.
+	int m = k;
+	
+	for ( ; *j; ++j, ++i )
+	{
+		int in = d(*i);
+		int jn = d(*j);
+
+		if ( in )
+			k/=in;
+		if ( jn )
+			k*=jn;
+		if ( m < k )
+			m = k;
+	//std::cout << m << " " << k << std::endl;
+	}
+
+	std::cout << m << std::endl;
+	return 0;
+}
+