题目链接:https://codeforces.com/contest/1265/problem/E 题目大意: 有 \(n\) 个步骤,第 \(i\) 个步骤成功的概率是 \(P_i\) ,每一步只有成功了才会进入下一步,失败了会从第 \(1\) 步重新开始测.请问成功的期望步数是多少? 解题思路: 设期望步数是 \(S\) ,则有公式如下: 实现代码如下: #include <bits/stdc++.h> using namespace std; typedef long long ll;…

A题 链接 思路分析: 因为只需要做到相邻的不相同,利用三个不同的字母是肯定可以实现的, 所以直接先将所有的问号进行替换,比如比前一个大1,如果与后面的冲突,则再加一 代码(写的很烂): #include <bits/stdc++.h> using namespace std; int check( string a) { for (int i = 0; i < a.length(); ++i) { if (i==0) { if (a[i]==a[i+1]) { return 0; }…

Codeforces Round #609 (Div. 2)前五题题解 补题补题…… C题写挂了好几个次,最后一题看了好久题解才懂……我太迟钝了…… 然后因为longlong调了半个小时…… A.Equation 题目大意:有一个数字n,让你给出任意两个合数a,b满足a - b = n. 我们知道大于2的偶数都是合数,那么如果n为奇数,只要n加上一个奇数合数一定也为合数,如果n为偶数,那么n加上一个偶数合数也一定为合数. 因为只求任意一组,就直接选择4,9,若为奇数输出 +n 和9,偶数输出 +…

// https://codeforces.com/contest/1265/problem/D /* 感觉像是遍历的思维构造题 有思路就很好做的 可以把该题想象成过山车或者山峰...... */ #include<iostream> #include<cstdio> using namespace std; int n; int cnt[5], last[5]; // last 是记录当前还有多少 0, 1, 2, 3 int ans[100005]; bool ok; int…

链接: https://codeforces.com/contest/1265/problem/E 题意: Creatnx has n mirrors, numbered from 1 to n. Every day, Creatnx asks exactly one mirror "Am I beautiful?". The i-th mirror will tell Creatnx that he is beautiful with probability pi100 for al…

链接: https://codeforces.com/contest/1265/problem/D 题意: An integer sequence is called beautiful if the difference between any two consecutive numbers is equal to 1. More formally, a sequence s1,s2,-,sn is beautiful if |si−si+1|=1 for all 1≤i≤n−1. Trans…

链接: https://codeforces.com/contest/1265/problem/C 题意: So the Beautiful Regional Contest (BeRC) has come to an end! n students took part in the contest. The final standings are already known: the participant in the i-th place solved pi problems. Since…

链接: https://codeforces.com/contest/1265/problem/B 题意: You are given a permutation p=[p1,p2,-,pn] of integers from 1 to n. Let's call the number m (1≤m≤n) beautiful, if there exists two indices l,r (1≤l≤r≤n), such that the numbers [pl,pl+1,-,pr] is a…

链接: https://codeforces.com/contest/1265/problem/A 题意: A string is called beautiful if no two consecutive characters are equal. For example, "ababcb", "a" and "abab" are beautiful strings, while "aaaaaa", "abaa&…

链接:http://codeforces.com/contest/1265 A. Beautiful String A string is called beautiful if no two consecutive characters are equal. For example, "ababcb", "a" and "abab" are beautiful strings, while "aaaaaa", "a…