清华大学出版社 TSINGHUA UNIVERSITY PRESS 算法总体思想 ·如果能够保存已解决的子问题的答案,而在需要时再 找出已求得的答案,就可以避免大量重复计算,从而 得到多项式时间算法。 Those who cannot remember the past are doomed to repeat it -George Santayana, The life of Reason Book Introduction and Reason in Common Sense(1905)5 • 如果能够保存已解决的子问题的答案，而在需要时再 找出已求得的答案，就可以避免大量重复计算，从而 得到多项式时间算法。 算法总体思想 = n n/2 T(n/4) T(n/4) T(n/4) T(n/4) n/2 n/2 T(n/4)T(n/4) n/2 T(n/4) T(n/4) T(n/4) T(n/4) T(n/4) Those who cannot remember the past T(n) are doomed to repeat it. -----George Santayana, The life of Reason, Book I: Introduction and Reason in Common Sense (1905)