常见面试笔试编程题目

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题目1：a^3 + b^3 + c^3 = d^3，a, b, c, d都是0－999之间的整数，写代码找出所有符合该条件的a,
b, c, d。

参考程序：以下程序在Linux上编译通过，共找出 3384 组答案，耗时约4秒

#include <iostream>
#include <stdlib.h>
#include <math.h>
#define N 1000
using namespace std;
typedef unsigned int uint;
typedef unsigned long long ullong;

/* Store cubic values, data
=n^3 */
ullong data
= {0};

/* Get the cubic value of n */
ullong cubic( uint n)
{
if(data
== 0)
{
data
= n*n*n;
}
return data
;
}

int main()
{
uint a,b,c,d;
ullong A,B,C,D;
double F;
for(d=0; d<N; d++)
{
D = cubic(d);
F = pow(D/3.0, 1.0/3);
for(a=(int)F; a<=d; a++)
{
A = cubic(a);
F = pow((D-A)/2.0, 1.0/3);
for(b=(int)F; b<=a; b++)
{
B = cubic(b);
if(A + B > D)
{
break;
}
F = pow(D-A-B, 1.0/3);
for(c=(int)F; c<=b; c++)
{
C = cubic(c);
if( A + B + C == D )
{
cout<< a << "^3 + " << b << "^3 + " << c << "^3 == " << d << "^3" << "\t:\t";
cout<< A << " + " << B << " + " << C << " == " << D << endl;
}else if(A + B + C > D)
{
break;
}
}
}
}
}
return 0;
}