Codeforces Round #719 Arranging The Sheep - Sort
Solution: We define the data structure below: static class Sheep { int suppose_pos, pos; } suppose_pos represent the position of this su…
Codeforces Round #719 To Go Or Not To Go? - BFS
Solution: This is a shortest paths problem. But do not use Dijkstra or SPFA to solve this problem. Because the time complex is $O(nm\cdot log(nm))$. Can get TLE with an extra $log$.…
Codeforces Round #719 Guess the K-th Zero (Hard version) - Segment tree
Solution Base on the easy version, we still binary search in the hard version. So, we query the sum of $[1, mid]$.Now the problem is, after each time, we need change the element from 0 to 1.…
Codeforces Global Round 14 ABCD Solutions
A. Phoenix and Gold Solution: If the sum of all numbers in w is x, then there is no solution. Because no matter what order, when $i=n$, the sum will be x.…
Codeforces Round #707 Going Home - Complexity Analysis
Solution: First. We can change $a_x + a_y = a_z + a_w$ to $a_x - a_w = a_z - a_y$. So the problem becomes a problem of finding two pairs so that their differ of each pair are equal.…
Educational Codeforces Round #108 ABCD Solutions
A. Red and Blue Beans Solution: Take the minimum value of $r$ and $b$ as $min$ and the maximum value as $max$.…
Educational Codeforces Round #105 ABCDE Solutions
A. ABC String Solution: Obviously, a certain letter appears twice as often as the other two letters. But for the convenience of implementation,…
Educational Codeforces Round #105 A-Z Graph - Graphs + Construction
Solution: It is obvious if the vertices can be repeated. Assuming there is a solution, there must be two edges v1->v2 and v2->v1.…
