题目链接:Round #587 题目答案:官方Editorial.My Solution A. Prefixes 题意:给一字符串,只含有'a'或'b',需要改变某些位置('a'变'b'或'b'变'a'),使得该字符串任意偶数长度前缀中'a'和'b'个数相等,求改变的最少次数以及更改后的字符串. 题解:遍历,判断s[2i]和s[2i+1]是否相等.如果相等,需要一次更改,并将其中一个改为不同字母. B. Shooting 题意:给\(n\)个编号\(1\)~\(n\)的射击目标,每个目标有不同的…

链接: https://codeforces.com/contest/1216/problem/D 题意: There were n types of swords in the theater basement which had been used during the plays. Moreover there were exactly x swords of each type. y people have broken into the theater basement and eac…

链接: https://codeforces.com/contest/1216/problem/C 题意: There is a white sheet of paper lying on a rectangle table. The sheet is a rectangle with its sides parallel to the sides of the table. If you will take a look from above and assume that the botto…

链接: https://codeforces.com/contest/1216/problem/B 题意: Recently Vasya decided to improve his pistol shooting skills. Today his coach offered him the following exercise. He placed n cans in a row on a table. Cans are numbered from left to right from 1…

链接: https://codeforces.com/contest/1216/problem/A 题意: Nikolay got a string s of even length n, which consists only of lowercase Latin letters 'a' and 'b'. Its positions are numbered from 1 to n. He wants to modify his string so that every its prefix…

https://codeforces.com/contest/1216/problem/A A. Prefixes 题意大概就是每个偶数位置前面的ab数目要相等,很水,被自己坑了 1是没看见要输出修改后的字符串,2是修改的写反了..3是忘记清零了?,生生把罚时拖的... 本来四分钟的题的..然后罚时+10分钟过题,我晕了,以后还是要再认真一点,比如说把样例测完.. #include<bits/stdc++.h> using namespace std; typedef long long ll…

题目:https://codeforces.com/contest/1216/problem/F 题意:一排有n个位置,我要让所有点都能联网,我有两种方式联网,第一种,我直接让当前点联网,花费为i,第二种,如果当前点的值为1,代表当前点可以放置一个路由器,范围 [i-k,i+k]都能连上网,花费为i,求最小花费是所有点都能连上网 思路:这个很容易看出是一个DP,我们设立dp[i],为前i个位置都能连上网的最小花费,因为设立一个路由器左右范围都可以联网,所以我们考虑设立路由器的右端点,如果i-k可…

C. White Sheet There is a white sheet of paper lying on a rectangle table. The sheet is a rectangle with its sides parallel to the sides of the table. If you will take a look from above and assume that the bottom left corner of the table has coordina…

传送门 •题意 先给一个白矩阵,再两个黑矩阵 如果两个黑矩阵能把白矩阵包含,则输出NO 否则输出YES •思路 计算几何题还是思维题呢? 想起了上初中高中做几何求面积的题 这个就类似于那样 包含的话分两种情况讨论,其他的不包含 ①白矩形在一个黑矩形内部 这种情况直接判断边界就可以 ②白矩形在两个黑矩形组合的图形内部 首先这个情况的前提是两个黑矩形必须能连接起来 白矩形和两个黑矩形分别会有重合,重合的地方可能会在此重合, 例如 白矩形(1 1 4 2)   黑1矩形(1 0 3 4)  黑2矩形(…

题意:给定一个字符串s 现在让你用最小的花费 覆盖所有区间 思路:dp[i]表示前i个全覆盖以后的花费 如果是0 我们只能直接加上当前位置的权值 否则 我们可以区间询问一下最小值 然后更新 #include <bits/stdc++.h> using namespace std; const int inf = 0x3f3f3f3f; const double eps = 1e-6; const int N = 2e5+7; typedef long long ll; const ll mod…