31 lines
735 B
C++
31 lines
735 B
C++
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Fig02_11.cpp - Recursive exponentiation algorithm, with a test program
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#include <iostream.h>
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bool isEven( int n )
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{
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return n % 2 == 0;
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}
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/* START: Fig02_11.txt*/
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long pow( long x, int n )
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{
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/* 1*/ if( n == 0 )
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/* 2*/ return 1;
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/* 3*/ if( n == 1 )
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/* 4*/ return x;
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/* 5*/ if( isEven( n ) )
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/* 6*/ return pow( x * x, n / 2 );
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else
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/* 7*/ return pow( x * x, n / 2 ) * x;
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}
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/* END */
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// Test program
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int main( )
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{
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cout << "2^21 = " << pow( 2, 21 ) << endl;
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cout << "2^30 = " << pow( 2, 30 ) << endl;
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return 0;
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}
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