B. Hamming Distance Sum time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Genos needs your help. He was asked to solve the following programming problem by Saitama: The length of some string…

Codeforces Round #336 (Div. 2) D. Zuma 题意:输入一个字符串:每次消去一个回文串,问最少消去的次数为多少? 思路:一般对于可以从中间操作的,一般看成是从头开始(因为只需要考虑一边),当考虑最左边的数时,有多少中消去方法?每种消去方法对结果的贡献又是多少?同时结果的区间又是怎么变化?这就是dp式子: 1.当单独消去这个元素时,dp[l][r] = 1 + dp[l+1][r]; 2.当存在一个k,l< k <= r,使得c[l] == c[k]时,可以认为在…

A. Saitama Destroys Hotel time limit per test:1 second memory limit per test:256 megabytes input:standard input output:standard output Saitama accidentally destroyed a hotel again. To repay the hotel company, Genos has volunteered to operate an eleva…

C. Chain Reaction 题目连接: http://www.codeforces.com/contest/608/problem/C Description There are n beacons located at distinct positions on a number line. The i-th beacon has position ai and power level bi. When the i-th beacon is activated, it destroys…

题目链接:https://codeforces.com/contest/608/problem/D 题意:给出n个宝石的颜色ci,现在有一个操作,就是子串的颜色是回文串的区间可以通过一次操作消去,问最少需要多少次操作可以消除所有的宝石.(每次操作消除一个回文串,最少操作次数清楚字符串) 题解:dp[l][r]表示区间(l,r)的最少操作次数,对于一个区间(l,r),有两种转移:①若存在c_l = c_i(l <= i <= r),可以由dp[l][i] + dp[i + 1][r]转移:②若c…

A. Mahmoud and Longest Uncommon Subsequence time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output While Mahmoud and Ehab were practicing for IOI, they found a problem which name was Longest comm…

题目链接 http://codeforces.com/contest/711/problem/C Description ZS the Coder and Chris the Baboon has arrived at Udayland! They walked in the park where n trees grow. They decided to be naughty and color the trees in the park. The trees are numbered wit…

D - Chloe and pleasant prizes 链接 http://codeforces.com/contest/743/problem/D 题面 Generous sponsors of the olympiad in which Chloe and Vladik took part allowed all the participants to choose a prize for them on their own. Christmas is coming, so sponso…

题目链接: http://www.codeforces.com/contest/675/problem/E 题意: 对于第i个站,它与i+1到a[i]的站有路相连,先在求所有站点i到站点j的最短距离之和(1<=i<j<=n) 题解: 这种所有可能都算一遍就会爆的题目,有可能是可以转化为去求每个数对最后答案的贡献,用一些组合计数的方法一般就可以很快算出来. 这里用dp[i]表示第i个站点到后面的所有站的最短距离之和,明显,i+1到a[i]的站,一步就可以到,对于后面的那些点,贪心一下,一定…

Roman and Numbers time limit per test 4 seconds memory limit per test 512 megabytes input standard input output standard output Roman is a young mathematician, very famous in Uzhland. Unfortunately, Sereja doesn't think so. To make Sereja change his…