题目链接: 570 E. Pig and Palindromes 题目描述: 有一个n*m的矩阵,每个小格子里面都有一个字母.Peppa the Pig想要从(1,1)到(n, m).因为Peppa the Pig是一个完美主义者,她想要她所经过的路径上的字母组成的字符串是一个回文串,现在Peppa the Pig想要知道有多少满足条件的走法? 解题思路: 因为经过路径上的字母要组成回文串,所以可以从(1,1),(n,m)同时开始dp.从(1,1)出发只能向下方和右方走,从(n,m)出发只能向上…

E. Pig and Palindromes   Peppa the Pig was walking and walked into the forest. What a strange coincidence! The forest has the shape of a rectangle, consisting of n rows and m columns. We enumerate the rows of the rectangle from top to bottom with num…

time limit per test4 seconds memory limit per test256 megabytes inputstandard input outputstandard output Peppa the Pig was walking and walked into the forest. What a strange coincidence! The forest has the shape of a rectangle, consisting of n rows…

D time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a lowercase English letter. Vertex 1 is the root of the tree, each of…

链接:https://codeforces.com/contest/570 A - Elections - [水] AC代码: #include<bits/stdc++.h> using namespace std; int n,m; ]; int main() { cin>>n>>m; ;i<=m;i++) { , id=; ,x;j<=n;j++) { cin>>x; if(x>mx) mx=x, id=j; } cnt[id]++;…

E. Pig and Palindromes Peppa the Pig was walking and walked into the forest. What a strange coincidence! The forest has the shape of a rectangle, consisting of n rows and m columns. We enumerate the rows of the rectangle from top to bottom with numbe…

[Codeforces 865C]Gotta Go Fast(期望dp+二分答案) 题面 一个游戏一共有n个关卡,对于第i关,用a[i]时间通过的概率为p[i],用b[i]通过的时间为1-p[i],每通过一关后可以选择继续下一关或者时间清0并从第一关开始,先要求通过所有关卡的时间和不能超过R才算彻底通关,问直到彻底通关位置的游戏时间的期望值为多少 分析 二分从头开始通关的用时期望mid 设\(dp[i][j]\)表示通前i关,当前时间为j的期望,倒推期望. 若超时重新开始,则\(dp[i][j]…

[CodeForces - 1225E]Rock Is Push [dp][前缀和] 标签:题解 codeforces题解 dp 前缀和 题目描述 Time limit 2000 ms Memory limit 524288 kB Source Technocup 2020 - Elimination Round 2 Tags binary search dp *2200 Site https://codeforces.com/problemset/problem/1225/E 题面 Examp…

[Codeforces 553E]Kyoya and Train(期望DP+Floyd+分治FFT) 题面 给出一个\(n\)个点\(m\)条边的有向图(可能有环),走每条边需要支付一个价格\(c_i\),需要的时间为\([1,T]\)中随机的整数,时间为\(j\)的概率为\(p_{i,j}\).从\(1\)出发走到\(n\),如果到\(n\)的时间超过\(T\),就需要再支付\(X\).找出一条路径,使得支付钱数的期望值最小.输出最小期望. \(n \leq 50,m \leq 100,T \…

题目链接:https://codeforces.com/problemset/problem/570/E 题意: 给出 $n \times m$ 的网格,每一格上有一个小写字母,现在从 $(1,1)$ 位置走到 $(n,m)$ 位置,要求经过路径构成一个回文串. 要求走路方向保证坐标不会减小(即只能往下或者往右走),要求你给出路径方案数目. 题解: 考虑 $f[x_1][y_1][x_2][y_2]$ 表示一端从 $(1,1)$ 出发,走到了 $(x_1,y_1)$,同时另一端从 $(n,m)$…