背包问题

#include<stdio.h>
#define N 7
#define S 15
int w[N+1]={0,1,4,3,4,5,2,7};
int knap(int s,int n)
{
 if(s==0) return 1;
 if(s<0||(s>0 && n<1)) return 0;
 if(knap(s-w[n],n-1)){
  printf("%4d",w[n]);
  return 1;
 }
 return knap(s,n-1);
}
main()
{
 if(knap(S,N)) printf("\nOK!\n");
 else printf("NO!\n");
}

#include <stdio.h>
#define N 7
#define S 15
typedef struct{
 int s;
 int n;
 int job;
}KNAPTP;
int w[N+1]={0,1,4,3,4,5,2,7};
int knap(int s,int n);
main()
{
 if(knap(S,N)) printf("OK!\n");
 else printf("NO!\n");
}
int knap(int s,int n)
{
 KNAPTP stack[100],x;
 int top,k,rep;
 x.s=s; x.n=n;
 x.job=0;
 top=1; stack[top]=x;
 k=0;
 while(top>=1&&!k){
  x=stack[top];
  rep=1;
  while(!k && rep){
   if(x.s==0) k=1;
   else if(x.s<0 || x.n<=0) rep=0;
   else{
    x.s=x.s-w[x.n--];
    x.job=1;
    stack[++top]=x;
   }
  }
  if(!k){
   rep=1;
   while(top>=1 && rep){
    x=stack[top--];
    if(x.job==1){
     x.s+=w[x.n+1];
     x.job=2;
     stack[++top]=x;
     rep=0;
    }
   }
  }
 }
 if(k){
  while(top >=1){
   x=stack[top--];
   if(x.job==1) printf("%4d\t",w[x.n+1]);
  }
 }
 return k;
}