AtCoder Beginner Contest 076

A - Rating Goal

---

Time limit : 2sec / Memory limit : 256MB

Score : 100 points

Problem Statement

Takahashi is a user of a site that hosts programming contests.
When a user competes in a contest, the rating of the user (not necessarily an integer) changes according to the performance of the user, as follows:

• Let the current rating of the user be a.
• Suppose that the performance of the user in the contest is b.
• Then, the new rating of the user will be the avarage of a and b.

For example, if a user with rating 1 competes in a contest and gives performance 1000, his/her new rating will be 500.5, the average of 1 and 1000.

Takahashi's current rating is R, and he wants his rating to be exactly G after the next contest.
Find the performance required to achieve it.

Constraints

• 0≤R,G≤4500
• All input values are integers.

---

Input

Input is given from Standard Input in the following format:

R
G

Output

Print the performance required to achieve the objective.

---

Sample Input 1

Copy

2002
2017

Sample Output 1

Copy

2032

Takahashi's current rating is 2002.
If his performance in the contest is 2032, his rating will be the average of 2002 and 2032, which is equal to the desired rating, 2017.

---

Sample Input 2

Copy

4500
0

Sample Output 2

Copy

-4500

Although the current and desired ratings are between 0 and 4500, the performance of a user can be below 0.

#include<algorithm>
#include<iostream>
#include<cstdio>
#include<map>
using namespace std;
 
const int N = 1000 + 5;
 
int c, n;
struct node{
    int total_time = 0, total_solve = 0, num;
    map<int, int> state;
}Node[N];
 
int main(){
    double a, b;
    cin >> a >> b;
    cout << b * 2 - a <<endl;
}

 

B - Addition and Multiplication

---

Time limit : 2sec / Memory limit : 256MB

Score : 200 points

Problem Statement

Square1001 has seen an electric bulletin board displaying the integer 1. He can perform the following operations A and B to change this value:

• Operation A: The displayed value is doubled.
• Operation B: The displayed value increases by K.

Square1001 needs to perform these operations N times in total. Find the minimum possible value displayed in the board after N operations.

Constraints

• 1≤N,K≤10
• All input values are integers.

---

Input

Input is given from Standard Input in the following format:

N
K

Output

Print the minimum possible value displayed in the board after N operations.

---

Sample Input 1

Copy

4
3

Sample Output 1

Copy

10

The value will be minimized when the operations are performed in the following order: A, A, B, B.
In this case, the value will change as follows: 1 → 2 → 4 → 7 → 10.

---

Sample Input 2

Copy

10
10

Sample Output 2

Copy

76

The value will be minimized when the operations are performed in the following order: A, A, A, A, B, B, B, B, B, B.
In this case, the value will change as follows: 1 → 2 → 4 → 8 → 16 → 26 → 36 → 46 → 56 → 66 → 76.

By the way, this contest is AtCoder Beginner Contest 076.

#include<algorithm>
#include<iostream>
#include<cstdio>
#include<map>
using namespace std;
 
 
int main(){
    int n, k;
    int a = 1;
    cin >> n >> k;
    for(int i = 1; i <= n; i++){
        if(a + k < 2 * a) a += k;
        else a *= 2;
    }
    cout << a << endl;
}

#include<bits/stdc++.h>
 
using namespace std;
 
int n, k;
 
int DFS(int n, int val){
    if(n == 0) return val;
    int a = DFS(n - 1, val * 2);
    int b = DFS(n - 1, val + k);
    return a > b ? b : a;
}
int main(){
    cin >> n >> k;
    cout << DFS(n, 1) << endl;
}

 

C - Dubious Document 2

---

Time limit : 2sec / Memory limit : 256MB

Score : 300 points

Problem Statement

E869120 found a chest which is likely to contain treasure.
However, the chest is locked. In order to open it, he needs to enter a string S consisting of lowercase English letters.
He also found a string S', which turns out to be the string S with some of its letters (possibly all or none) replaced with ?.

One more thing he found is a sheet of paper with the following facts written on it:

• Condition 1: The string S contains a string T as a contiguous substring.
• Condition 2: S is the lexicographically smallest string among the ones that satisfy Condition 1.

Print the string S.
If such a string does not exist, print UNRESTORABLE.

Constraints

• 1≤|S'|,|T|≤50
• S' consists of lowercase English letters and ?.
• T consists of lowercase English letters.

---

Input

Input is given from Standard Input in the following format:

S
T'

Output

Print the string S.
If such a string does not exist, print UNRESTORABLE instead.

---

Sample Input 1

Copy

?tc????
coder

Sample Output 1

Copy

atcoder

There are 26 strings that satisfy Condition 1: atcoder, btcoder, ctcoder,..., ztcoder. Among them, the lexicographically smallest is atcoder, so we can say S=atcoder.

---

Sample Input 2

Copy

??p??d??
abc

Sample Output 2

Copy

UNRESTORABLE

There is no string that satisfies Condition 1, so the string S does not exist.

#include<algorithm>
#include<iostream>
#include<cstdio>
#include<map>
#include<set>
using namespace std;
string s, t;
set<string> S;
 
void Work(){
    int lens = s.size();
    int lent = t.size();
    for(int i = 0; i < lens; i++){
        if(s[i] == '?' || s[i] == t[0]){
            string tmp = s;
            for(int j = 0; j < i; j++) if(tmp[j] == '?') tmp[j] ='a';
            bool can = false;
            for(int j = 0; j < lent; j++){
                if(tmp[i+j]!= '?' && tmp[i+j] != t[j]) break;
                tmp[i+j] = t[j];
                if(j == lent - 1) can = true;
            }
            if(can){
                for(int j = i + lent; j < lens; j++) if(tmp[j] == '?') tmp[j] = 'a';
                S.insert(tmp);
            }
        }
    }
    if(S.size() == 0) cout << "UNRESTORABLE" << endl;
    else cout << *S.begin() << endl;
}
int main(){
    cin >> s >> t;
    Work();
}