（回溯法）和为n的所有不增正整数和式分解算法

#include <iostream>
#include <stdio.h>

using namespace std;

#define N 100

void subSetOfSumN(int a[],int sum,int k){
    for(int i=sum;i>=1;i--){
        if(i<=a[k-1]){
            a[k]=i;
            if(i==sum){
                printf("%d=%d",a[0],a[1]);
                for(int p=2;p<=k;p++)
                    printf("+%d",a[p]);
                printf("\n");
            }
            else
                subSetOfSumN(a,sum-i,k+1);
        }
    }
}

int main()
{
    int n,a[N];
    printf("Please input an integer n(1<=n<=20):");
    scanf("%d",&n);
    a[0]=n;
    printf("The result of nonDescend integer factorization is:\n");
    subSetOfSumN(a,n,1);
    return 0;
}