输入两个整数n和m, 从数列1,2,...,n中任意选择几个数,使其和等于m, 要求编写程序输出所有的组合

01背包问题

#include<iostream.h>
#include<malloc.h>

int length;

void PrintSolutions(int *flag)
{
    for (int i=1; i<=length; i++)
    {
        if (flag[i] == 1)
        {
            cout << i << "  ";
        }
    }
    cout << endl;
}

void BagProblem(int m, int n, int *flag)
{
    if(n<1 || m<1)
        return;
    if(m < n)
        n = m;
    if (n == m)
    {
        flag[n] = 1;
        PrintSolutions(flag);
        flag[n] = 0;
    }
    flag[n] = 1;
    BagProblem(m-n,n-1,flag);
    flag[n] = 0;

    BagProblem(m,n-1,flag);
}

void main()
{	
	int n=10,m=12;
	length=n;
	int *flag = (int *)malloc(sizeof(int)*(n+1));
	BagProblem(m,n,flag);
	free(flag);
}