T1 "greedy"
Watched 25 minutes die a few examples, people do not mistakenly think the remaining accumulated, then punched a positive solution has been shot and violence against AC, and then think they have the A
WA80, very grateful to the topic of human data
Positive Solutions: emotional understanding of what would happen if many points hit province
Then the next will not need to add more new,
And sum_a certain, so direct sequencing on the line
T2 "combinatorics"
This is obviously an entrance math problem, $ (C_n ^ m) = 2 ^ m * ^ C_n ^ {nm} $ C_n
Next to go find mathematical laws are futile, then you can consider the actual meaning,
Is now selected from the n items in the m, then select the nm In another article in the n,
That sum is $ C_ {2n} ^ m $
T3 "palindromic sequence"
The last test palindrome is a mathematical problem, this time on the test several yy a palindrome string Qiufa,
Then write a time complexity $ O (n) $ space $ O (n ^ 2) $ find whether lr palindromic sequence, positive solution is g [i + 1] [j-1] Push to g [i] [j]
Then I used to sort and lower_bound $ O (n ^ 2logn) $ to the summation,
Dp can be used to find a very simple f [i] [j] = f [i + 1] [j] + f [i] [j-1] -f [i + 1] [j-1] + g [i] [j]