The Triangle
Time Limit:1000MS Memory Limit:10000K
Description
7
3 8
8 1 0
2 7 4 4
4 5 2 6 5
(Figure 1)
Figure 1 shows a number triangle. Write a program that calculates the highest sum of numbers passed on a route that starts at the top and ends somewhere on the base. Each step can go either diagonally down to the left or diagonally down to the right.
Input
Your program is to read from standard input. The first line contains one integer N: the number of rows in the triangle. The following N lines describe the data of the triangle. The number of rows in the triangle is > 1 but <= 100. The numbers in the triangle, all integers, are between 0 and 99.
Output
Your program is to write to standard output. The highest sum is written as an integer.
Sample Input5
7
3 8
8 1 0
2 7 4 4
4 5 2 6 5
Sample Output30
Source
IOI 1994























































這道題目,過得好辛苦,從開始的遞歸,到遞推加回溯,到窮舉,到窮舉加剪枝,結(jié)果就從TLE->TLE->TLE->WA. 一直用著要保留路徑的方法,所以怎么也做不出來(lái),后來(lái)?yè)Q了個(gè)思維角度,保存每一步的結(jié)果,動(dòng)態(tài)規(guī)劃,終于就AC了。做了這題,另我復(fù)習(xí)了好幾種方法,也對(duì)DP有了深得認(rèn)識(shí),可以說這是搞競(jìng)賽的好題目,經(jīng)典,推薦!!