关于舞蹈链速度

bool dance(int x){
		if (!R[0]){
			ans = x;
			return 1;
		}
		int c = R[0];
		for (int i=R[0];i != 0;i = R[i])
		    if (siz[i] < siz[c])
		        c = i;//less 1;
	    remove(c);
	    //choose a column with the less 1
	    for (int i = D[c];i != c;i = D[i]){
	    	stk[x] = row[i];
	    	//choose a row with the less 1
	    	//delete the row and the col with 1
	    	for (int j = R[i];j != i;j = R[j])
	    	    remove(col[j]);
	    	if (dance(x + 1))
	    	    return 1;
	    	for (int j = L[i];j != i;j = L[j])
	    	    recover(col[j]);
		}
		recover(c);
		return 0;
	}