40 lines
673 B
C++
40 lines
673 B
C++
/* Check cf5-opt.vim defs.
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VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
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VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
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*/
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#include <iostream>
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/*
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Multiples of 3 and 5
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Problem 1
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If we list all the natural numbers below 10 that are multiples of 3 or 5, we
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get 3, 5, 6 and 9. The sum of these multiples is 23.
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Find the sum of all the multiples of 3 or 5 below 1000.
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Solution:
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233168
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*/
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/*
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Sum of all numbers below n multiple of m
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*/
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int sum(int n, int m )
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{
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int c = n/m;
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return m*c*(c+1)/2;
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}
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int main ( void )
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{
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const int l = 999;
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const int o1 = 3;
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const int o2 = 5;
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int s = sum( l, o1 ) + sum( l, o2 ) - sum( l, o1*o2 );
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std::cout << s << std::endl;
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return 0;
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}
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