#include <stdbool.h>
#include <stdlib.h>

#include "subset.h"

//Initialize the fixed subset iterator
void subsetInitSize(Subset* subset, int size, int n){
	subset->size = size;
	subset->n = n;
	int i=0;
	for(i=0;i<n-size;i++){
		subset->elem[i]=false;
	}
	for(;i<n;i++){
		subset->elem[i]=true;
	}
}
//Initialize the subset iterator
void subsetInit(Subset* subset,int n){
	subset->size = n;
	subset->n = n;
	subset->elem = malloc(sizeof(bool)*n);
	for(int i=0;i<n;i++)subset->elem[i]=true;
}
void subsetFree(Subset* subset){
	free(subset->elem);
}
bool subsetIterate(Subset* subset){
	if(subset->size==0)return false;
	if(!fixedSizeSubsetIterate(subset)){
		subsetInitSize(subset,subset->size-1,subset->n);
	}
	return true;
}
bool fixedSizeSubsetIterate(Subset* subset){
	int i=subset->n-1;
	for(int j=0; j<subset->n-subset->size; j++){
		for(;subset->elem[i];i--);
		if(j<subset->n-i-1){
			int k;
			subset->elem[i]=true;
			for(k=i+1;k<=i+1+j;k++)
				subset->elem[k] = false;
			for(;k<subset->n;k++)
				subset->elem[k] = true;
			return true;
		}
		i--;
	}
	return false;
}