xuanweiace的博客

    这题第一思路显然dfs，但是最近想了一下可以用next_permutation做，结果TLE了，究其原因，就是深搜的时候剪枝做的比较好，所以运行的时间一对比（样例是n=18），会发现dfs的解法程序在不停的输出数据，但是STL的却仅仅是在闪光标。    得结论：有的题剪枝的十分优雅（比如这题，如果1 2 判断不成立，那么第二个数放2这一大支直接剪掉了），便不能用next_permutati...

题干：Mr Wang wants some boys to help him with a project. Because the project is rather complex, the more boys come, the better it will be. Of course there are certain requirements. Mr Wang selected a ro...

题干：Given a set of sticks of various lengths, is it possible to join them end-to-end to form a square? InputThe first line of input contains N, the number of test cases. Each test case begins wit...

题干：George took sticks of the same length and cut them randomly until all parts became at most 50 units long. Now he wants to return sticks to the original state, but he forgot how many sticks he had...

题干：Limak is an old brown bear. He often plays poker with his friends. Today they went to a casino. There are n players (including Limak himself) and right now all of them have bids on the table. i-t...

题干：Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky ...