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虽然AC了,不过还是有点质疑

Posted by new_star at 2008-02-18 07:10:56 on Problem 1011 and last updated at 2008-02-18 07:12:09
//木棍长度已按升序排序,已经完成k根,第k+1根已完成长度ll,应该用t以后的木棍填充
bool search( int k, int ll, int t )
{	int p;
	if ( k == num ) return true;
	for ( int i = t; i <= sticksNum; i++ ) {
		if ( ! used[i] ) {
			if ( (p = ll+stick[i]) < goalLen ) {
				used[i] = true;
				if ( search( k, p, i+1 ) ) return  true;
				used[i] = false;
			}
			else if( p == goalLen ) {
				used[i] = true;
				if( search( k+1, 0, 1 ) ) return true;
				used[i] = 0;
				break;//开始没有这条语句,结果TLE
			}
			if ( ll == 0 ) break;
		}
	}
	return false;
}
疑问:如果存在某个长度正好填满一根原始木棍,就真的不该考虑其他长度的木棍了么?
      刘泸佳的书上是认可的,如果能用更长的原始木棍,长度将会超过t,显然不行;
      如果使用更短的,即使存在某个也能填满木棍的方法,该方法也一定不会比用大木头更有希望获得可行解。
      这样,一旦发现某木棍能填满该原始木棍,就没有必要考虑其他木棍了,
      时间效率大大提高,数据不到0.01秒解出。
      正准备证明这个结论,大家一起讨论下

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