Robert Anderson's Blog

蠻簡單的一題

不過蠻有趣的

先求SCC

再來你要求是不是有一個group

DFS搜尋

State只有3^(N-1)種

推導出公式

L(2a + L - 1)/2 = N

Idea #1: Heuristic Pruning

The easiest and most common use for heuristic functions is to prune the search space. Assume the problem is to find the solution with the minimum total cost. With an admissible heuristic function, if the cost of the current solution thus far is A, and the heuristic function returns B, then the best possible solution which is a child of the current solution is A+B. If the a solution has been found with cost C, where C < A+B, there is no reason to continue searching for a solution from this state.

This is simple to code and debug (assuming one starts with a working, but slow, program, which is how this should be used) and can yield immense returns in terms of run-time. It is especially helpful with depth-first search with iterative deepening.

先做好Precalculation

時間複雜度是O(maxN)

判斷有點多

以下說明有哪些不合法情況

很簡單的一題

如果你用其他方法做（應該都比較麻煩）

先找出1 - 10000的質數

再來就是求Consecutive的Sum

先預算好所有答案

因為他規定number不能recurring