一个小疑问

void work()
{
	for(int i = 1;i < 185;i ++)
		n2[i] = i * i;
	
	f[0][0] = 1;//初始化 
	for(int i = 1;n2[i] <= 32768;i ++)
		for(int k = n2[i];k <= 32768;k ++)
			for(int j = 1;j <= 4;j ++)//j从1开始 
				f[k][j] += f[k - n2[i]][j - 1];
}

void work()
{
	for(int i = 1;i < 185;i ++)
		n2[i] = i * i,f[n2[i]][1] = 1;//初始化
	
	for(int i = 1;n2[i] <= 32768;i ++)
		for(int k = n2[i];k <= 32768;k ++)
			for(int j = 2;j <= 4;j ++)//j从2开始
				f[k][j] += f[k - n2[i]][j - 1];
}

void work()
{
	for(int i = 1;i < 185;i ++)
		n2[i] = i * i,f[n2[i]][1] = 1;
	
	for(int j = 2;j <= 4;j ++)
		for(int k = 1;k <= 32768;k ++)
			for(int i = 1;n2[i] <= k;i ++) 
				f[k][j] += f[k - n2[i]][j - 1];
  //先j再k再i
}