首次提问者。今天早上我意识到,我知道如何通过简单的递归调用来执行感兴趣的任务。问题是全局集合没有被任何调用S.insert(n)所改变。我希望有一种直接的方法来重写它,以便用找到的数字填满集合。那么,问题是,如何做到这一点?
下面是我编写的函数,稍后调用它的片段,以及输出的相关部分。我对来自cerr命令的行完全满意,因此只需将这些值(每行中的第一个和第三个)放入STL集。我对如何做那部分的初步猜测不够好。..............................................................
void insert_primitive_reps(unsigned int a, unsigned int h, unsigned int b, unsigned int M, set<unsigned int> S)
{
cerr << setw(12) << a << setw(12) << h << setw(12) << b << " insert_primitive_reps" << endl;
if ( a <= M )
{
S.insert(a);
if ( b <= M )
{
S.insert(b);
if ( a <= M - b && h <= M - a - b)
{
if( a <= M - a - h ) insert_primitive_reps(a, h + 2 * a, a + b + h, M, S);
if( b <= M - b - h ) insert_primitive_reps(a + b + h, h + 2 * b,b, M, S);
// comment: once a+b+h <= M, min(2a+h, 2b+h) <= M
} // if a + b + h
} // if b
} // if a
} // end insert_primitive_rep
.....................................
set<unsigned int> S;
insert_primitive_reps(1,3,1,100, S);
cout << S.size() << endl;
set<unsigned int>::iterator iterU;
for(iterU = S.begin() ; iterU != S.end() ; ++iterU)
{
unsigned int p = *iterU;
cout << setw(12) << p << Factored(p) << endl;
}
......................................
June 7 2014
1 3 1 insert_primitive_reps
1 5 5 insert_primitive_reps
1 7 11 insert_primitive_reps
1 9 19 insert_primitive_reps
1 11 29 insert_primitive_reps
1 13 41 insert_primitive_reps
1 15 55 insert_primitive_reps
1 17 71 insert_primitive_reps
1 19 89 insert_primitive_reps
55 95 41 insert_primitive_reps
41 69 29 insert_primitive_reps
29 47 19 insert_primitive_reps
95 85 19 insert_primitive_reps
19 29 11 insert_primitive_reps
19 67 59 insert_primitive_reps
59 51 11 insert_primitive_reps
11 15 5 insert_primitive_reps
11 37 31 insert_primitive_reps
11 59 79 insert_primitive_reps
79 99 31 insert_primitive_reps
31 25 5 insert_primitive_reps
31 87 61 insert_primitive_reps
61 35 5 insert_primitive_reps
5 5 1 insert_primitive_reps
5 15 11 insert_primitive_reps
5 25 31 insert_primitive_reps
5 35 61 insert_primitive_reps
61 87 31 insert_primitive_reps
31 37 11 insert_primitive_reps
31 99 79 insert_primitive_reps
79 59 11 insert_primitive_reps
11 7 1 insert_primitive_reps
11 29 19 insert_primitive_reps
11 51 59 insert_primitive_reps
59 67 19 insert_primitive_reps
19 9 1 insert_primitive_reps
19 47 29 insert_primitive_reps
19 85 95 insert_primitive_reps
29 11 1 insert_primitive_reps
29 69 41 insert_primitive_reps
41 13 1 insert_primitive_reps
41 95 55 insert_primitive_reps
55 15 1 insert_primitive_reps
71 17 1 insert_primitive_reps
89 19 1 insert_primitive_reps
S size 0
jagy@phobeusjunior:~$
.........................................
来自朋友的帮助,加上在Deitel和Deitel的书中查找"解引用"的一些提示:
....................................
void insert_primitive_reps(unsigned int a, unsigned int h, unsigned int b, unsigned int M, set<unsigned int> *S)
{
cerr << setw(12) << a << setw(12) << h << setw(12) << b << " insert_primitive_reps" << endl;
if ( a <= M )
{
(*S).insert(a);
if ( b <= M )
{
(*S).insert(b);
if ( a <= M - b && h <= M - a - b)
{
if( a <= M - a - h ) insert_primitive_reps(a, h + 2 * a, a + b + h, M, S);
if( b <= M - b - h ) insert_primitive_reps(a + b + h, h + 2 * b,b, M, S);
// comment: once a+b+h <= M, min(2a+h, 2b+h) <= M
} // if a + b + h
} // if b
} // if a
} // end insert_primitive_rep
...............................
cout << endl << " June 7 2014 " << endl << endl;
set<unsigned int> S;
insert_primitive_reps(1,3,1,100, &S);
cout << " S size " << S.size() << endl;
set<unsigned int>::iterator iterU;
for(iterU = S.begin() ; iterU != S.end() ; ++iterU)
{
unsigned int p = *iterU;
cout << setw(12) << p << Factored(p) << endl;
}
.................................
June 7 2014
1 3 1 insert_primitive_reps
1 5 5 insert_primitive_reps
1 7 11 insert_primitive_reps
1 9 19 insert_primitive_reps
1 11 29 insert_primitive_reps
1 13 41 insert_primitive_reps
1 15 55 insert_primitive_reps
1 17 71 insert_primitive_reps
1 19 89 insert_primitive_reps
55 95 41 insert_primitive_reps
41 69 29 insert_primitive_reps
29 47 19 insert_primitive_reps
95 85 19 insert_primitive_reps
19 29 11 insert_primitive_reps
19 67 59 insert_primitive_reps
59 51 11 insert_primitive_reps
11 15 5 insert_primitive_reps
11 37 31 insert_primitive_reps
11 59 79 insert_primitive_reps
79 99 31 insert_primitive_reps
31 25 5 insert_primitive_reps
31 87 61 insert_primitive_reps
61 35 5 insert_primitive_reps
5 5 1 insert_primitive_reps
5 15 11 insert_primitive_reps
5 25 31 insert_primitive_reps
5 35 61 insert_primitive_reps
61 87 31 insert_primitive_reps
31 37 11 insert_primitive_reps
31 99 79 insert_primitive_reps
79 59 11 insert_primitive_reps
11 7 1 insert_primitive_reps
11 29 19 insert_primitive_reps
11 51 59 insert_primitive_reps
59 67 19 insert_primitive_reps
19 9 1 insert_primitive_reps
19 47 29 insert_primitive_reps
19 85 95 insert_primitive_reps
29 11 1 insert_primitive_reps
29 69 41 insert_primitive_reps
41 13 1 insert_primitive_reps
41 95 55 insert_primitive_reps
55 15 1 insert_primitive_reps
71 17 1 insert_primitive_reps
89 19 1 insert_primitive_reps
S size 14
1 = 1
5 = 5
11 = 11
19 = 19
29 = 29
31 = 31
41 = 41
55 = 5 * 11
59 = 59
61 = 61
71 = 71
79 = 79
89 = 89
95 = 5 * 19
jagy@phobeusjunior:~$
.................................