Personal blog ：Eloi- Still moving forward .

21.12.13 Monday

21.12.14 Tuesday

21.12.15 Wednesday

21.12.16 Thursday

• Codeforces Round #761 (Div. 2)
  • C. Paprika and Permutation
    — Simple greed —
    The question ： Give you a sequence of numbers to pass mod x The operation turns it into n The whole arrangement
    We can consider greedy algorithm
    1-n Don't touch it , Of course, if there are duplicates, they will also enter the priority queue
    The rest goes to the priority queue
    Analysis is easy to know ： The larger the number, the better the transformation is , Have a linear relationship
    So then we judge from 1-n Whether the non-existent number in the queue can be determined by top Just convert

21.12.17 Friday

• Educational Codeforces Round 119 (Rated for Div. 2)（VP）
  • E. Replace the Numbers:
    The question ：q Group operation , There are two kinds of 1. Push a number into the end of the array x
    2. Put... In the array x All into y
    Ideas ： Because of the operation 2 With no aftereffect , We can think backwards , Reverse treatment
    Inquiry operation 2 becomes ——“ Then press x When I press in y”
    You can design one flag Array tag corresponds to —— To press in x When I press into who
    At the beginning, it's all about pushing yourself
    Note that the second operation here is ：flag[Q[i].a]=flag[Q[i].b];
    instead of ：flag[Q[i].a]=Q[i].b;
    Avoid, for example, I want to press 4, But it was previously stipulated to press 4 When I press in 3
    But the previous regulation stipulates that it is necessary to press 3 When I press in 2

21.12.18 Saturday

• Codeforces Round #581 (Div. 2)
  • C. Anna, Svyatoslav and Maps
    ---- All source shortest path floyed Algorithm -----
    The question ： Here's a digraph for you , A sequence of paths ,
    Let you find a sequence of nodes ,
    Its shortest path sequence is the above path sequence
    Ideas ： For a given path sequence , Second to second m-1 Each node judges
    Is it irreplaceable
    1. When judging the first irreplaceable point before this point
    The shortest path to the next point of the judgment point is the path, which can be replaced
    2. When judging the first irreplaceable point before this point
    When the shortest path to the next point of the judgment point is not the path, it cannot be replaced
    Alternatively delete
    Output the result

21.12.19 Sunday