题目连接:Game Of Rotation Mark is an undergraduate student and he is interested in rotation. A conveyor belt competition is going on in the town which Mark wants to win. In the competition, there's A conveyor belt which can be represented as a strip of 1…
题目链接:Running Time of Quicksort Challenge In practice, how much faster is Quicksort (in-place) than Insertion Sort? Compare the running time of the two algorithms by counting how many swaps or shifts each one takes to sort an array, and output the dif…
在jxzz上发现的一个做题网站,每周都有训练题,题目质量……前三题比较水,后面好神啊,而且类型差不多,这周似乎是计数专题…… Army Game 然后给出n*m,问需要多少个小红点能全部占领 解法:乘法... Best Divisor 给一个数,问一个数的约数中数字和最大的约数. 解法:直接分解质因数就可以啦. Twins 孪生质数定义为两个质数之差为2,问n,m之间有多少个孪生质数(n<=m<=10^9,m-n<=10^6) 解法:显然直接判断区间内相邻的两个奇数是否为质数就可以啦.然…
题目链接:Coin on the Table 一开始想用DFS做的,做了好久都超时. 看了题解才明白要用动态规划. 设置一个三维数组dp,其中dp[i][j][k]表示在时间k到达(i,j)所需要做的最小改动,那么递推式如下: 图片来源:Editorial,其中当从周围的格子可以直接移动到(i,j)时,delta=0:否则,需要改变周围格子的方向符号,delta=1. 即k-1时刻在(i,.j)周围的四个格子,然后在k时刻移动到(i,j).并且,看这四个格子中的方向符号是否直接可以完成这次移动,…