Educational Codeforces Round 51 (Rated for Div. 2) A,B,C 题解
传送门
A. Vasya And Password
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Vasya came up with a password to register for EatForces — a string ss. The password in EatForces should be a string, consisting of lowercase and uppercase Latin letters and digits.
But since EatForces takes care of the security of its users, user passwords must contain at least one digit, at least one uppercase Latin letter and at least one lowercase Latin letter. For example, the passwords "abaCABA12", "Z7q" and "3R24m" are valid, and the passwords "qwerty", "qwerty12345" and "Password" are not.
A substring of string ss is a string x=slsl+1…sl+len−1(1≤l≤|s|,0≤len≤|s|−l+1)x=slsl+1…sl+len−1(1≤l≤|s|,0≤len≤|s|−l+1). lenlen is the length of the substring. Note that the empty string is also considered a substring of ss, it has the length 00.
Vasya's password, however, may come too weak for the security settings of EatForces. He likes his password, so he wants to replace some its substring with another string of the same length in order to satisfy the above conditions. This operation should be performed exactly once, and the chosen string should have the minimal possible length.
Note that the length of ss should not change after the replacement of the substring, and the string itself should contain only lowercase and uppercase Latin letters and digits.
Input
The first line contains a single integer TT (1≤T≤1001≤T≤100) — the number of testcases.
Each of the next TT lines contains the initial password s (3≤|s|≤100)s (3≤|s|≤100), consisting of lowercase and uppercase Latin letters and digits.
Only T=1T=1 is allowed for hacks.
Output
For each testcase print a renewed password, which corresponds to given conditions.
The length of the replaced substring is calculated as following: write down all the changed positions. If there are none, then the length is 00. Otherwise the length is the difference between the first and the last changed position plus one. For example, the length of the changed substring between the passwords "abcdef" →→ "a7cdEf" is 44, because the changed positions are 22 and 55, thus (5−2)+1=4(5−2)+1=4.
It is guaranteed that such a password always exists.
If there are several suitable passwords — output any of them.
Example
input
Copy
2
abcDCE
htQw27
output
Copy
abcD4E
htQw27
Note
In the first example Vasya's password lacks a digit, he replaces substring "C" with "4" and gets password "abcD4E". That means, he changed the substring of length 1.
In the second example Vasya's password is ok from the beginning, and nothing has to be changed. That is the same as replacing the empty substring with another empty substring (length 0).
题意：
- 最少的操作使原串变成有数字+大小写字母的串。
#include
#include
#include
#include
#include
using namespace std;
int main()
{
int w;
cin>>w;
while(w--)
{
int n=0,m=0,t=0;
string s;
cin>>s;
for(int i=0;i='a'&&s[i]<='z')
{
n++;
}
if(s[i]>='A'&&s[i]<='Z')
{
m++;
}
if(s[i]>='0'&&s[i]<='9')
{
t++;
}
}
for(int i=0;i='a'&&s[i]<='z'&&n>1)
{
if(m==0)
{
m++;
s[i]='A';
continue;
}
if(t==0)
{
t++;
s[i]='1';
continue;
}
}
if(s[i]>='A'&&s[i]<='Z'&&m>1)
{
if(n==0)
{
n++;
s[i]='a';
continue;
}
if(t==0)
{
t++;
s[i]='1';
continue;
}
}
if(s[i]>='0'&&s[i]<='9'&&t>1)
{
if(n==0)
{
n++;
s[i]='a';
continue;
}
if(m==0)
{
m++;
s[i]='A';
continue;
}
}
}
cout< B. Relatively Prime Pairs
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
You are given a set of all integers from ll to rr inclusive, l You want to split these numbers into exactly r−l+12r−l+12 pairs in such a way that for each pair (i,j)(i,j) the greatest common divisor of ii and jj is equal to 11. Each number should appear in exactly one of the pairs. Print the resulting pairs or output that no solution exists. If there are multiple solutions, print any of them. Input The only line contains two integers ll and rr (1≤l Output If any solution exists, print "YES" in the first line. Each of the next r−l+12r−l+12 lines should contain some pair of integers. GCD of numbers in each pair should be equal to 11. All (r−l+1)(r−l+1) numbers should be pairwise distinct and should have values from ll to rr inclusive. If there are multiple solutions, print any of them. If there exists no solution, print "NO". Example input Copy output Copy 题意： C. Vasya and Multisets time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Vasya has a multiset ss consisting of nn integer numbers. Vasya calls some number xx nice if it appears in the multiset exactly once. For example, multiset {1,1,2,3,3,3,4}{1,1,2,3,3,3,4} contains nice numbers 22 and 44. Vasya wants to split multiset ss into two multisets aa and bb (one of which may be empty) in such a way that the quantity of nice numbers in multiset aa would be the same as the quantity of nice numbers in multiset bb (the quantity of numbers to appear exactly once in multiset aaand the quantity of numbers to appear exactly once in multiset bb). Input The first line contains a single integer n (2≤n≤100)n (2≤n≤100). The second line contains nn integers s1,s2,…sn (1≤si≤100)s1,s2,…sn (1≤si≤100) — the multiset ss. Output If there exists no split of ss to satisfy the given requirements, then print "NO" in the first line. Otherwise print "YES" in the first line. The second line should contain a string, consisting of nn characters. ii-th character should be equal to 'A' if the ii-th element of multiset ssgoes to multiset aa and 'B' if if the ii-th element of multiset ss goes to multiset bb. Elements are numbered from 11 to nn in the order they are given in the input. If there exist multiple solutions, then print any of them. Examples input Copy output Copy input Copy output Copy 题意： 题解： 若这组数里面只出现一次的数一共有偶数个说明可以组成 若这组数里面只出现一次的数一共有奇数个 并且出现次数大于三的个数为0 说明不可以组成 这组数里面只出现一次的数一共有奇数个 并且出现次数大于三的个数不为0 说明可以组成 比如 出现了三次5 可以将一个5放在一个数组 其他的放在另一个数组 这样就可以看成出现次数为1的个数为偶数了 1 8
YES
2 7
4 1
3 8
6 5
#include 4
3 5 7 1
YES
BABA
3
3 5 1
NO
#include