AtCoder Beginner Contest 373（ABCDEF 题）视频讲解

A - September

Problem Statement

There are $12$ strings $S_1,S_2,\dots ,S_{12}$ consisting of lowercase English letters.
Find how many integers $i$ $(1\le i\le 12)$ satisfy that the length of $S_i$ is $i$.

Constraints

Each $S_i$ is a string of length between $1$ and $100$, inclusive, consisting of lowercase English letters. $(1\le i\le 12)$

Input

The input is given from Standard Input in the following format:

$S_1$
$S_2$
$⋮$
$S_{12}$

Output

Print the number of integers $i$ $(1\le i\le 12)$ such that the length of $S_i$ is $i$.

Sample Input 1

january
february
march
april
may
june
july
august
september
october
november
december

Sample Output 1

1

There is only one integer $i$ such that the length of $S_i$ is $i$: $9$. Thus, print 1.

Sample Input 2

ve
inrtfa
npccxva
djiq
lmbkktngaovl
mlfiv
fmbvcmuxuwggfq
qgmtwxmb
jii
ts
bfxrvs
eqvy

Sample Output 2

2

There are two integers $i$ such that the length of $S_i$ is $i$: $4$ and $8$. Thus, print 2.

Solution

具体见文末视频。

---

Code

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second

using namespace std;

signed main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

	int res = 0;
	for (int i = 1; i <= 12; i ++) {
		string s;
		cin >> s;
		if (s.size() == i) res ++;
	}
	
	cout << res << endl;

	return 0;
}

B - 1D Keyboard

Problem Statement

There is a keyboard with $26$ keys arranged on a number line.
The arrangement of this keyboard is represented by a string $S$, which is a permutation of ABCDEFGHIJKLMNOPQRSTUVWXYZ.
The key corresponding to the character $S_x$ is located at coordinate $x$ $(1\le x\le 26)$. Here, $S_x$ denotes the $x$-th character of $S$.
You will use this keyboard to input ABCDEFGHIJKLMNOPQRSTUVWXYZ in this order, typing each letter exactly once with your right index finger.
To input a character, you need to move your finger to the coordinate of the key corresponding to that character and press the key.
Initially, your finger is at the coordinate of the key corresponding to A. Find the minimal possible total traveled distance of your finger from pressing the key for A to pressing the key for Z. Here, pressing a key does not contribute to the distance.

Constraints

$S$ is a permutation of ABCDEFGHIJKLMNOPQRSTUVWXYZ.

Input

The input is given from Standard Input in the following format:

$S$

Output

Print the answer.

Sample Input 1

ABCDEFGHIJKLMNOPQRSTUVWXYZ

Sample Output 1

25

From pressing the key for A to pressing the key for Z, you need to move your finger $1$ unit at a time in the positive direction, resulting in a total traveled distance of $25$. It is impossible to press all keys with a total traveled distance less than $25$, so print 25.

Sample Input 2

MGJYIZDKSBHPVENFLQURTCWOAX

Sample Output 2

223

Solution

具体见文末视频。

Code

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second

using namespace std;

signed main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

	int res = 0;
	unordered_map<char, int> idx;
	for (int i = 1; i <= 26; i ++) {
		char x;
		cin >> x, idx[x] = i;
	}
	for (char i = 'A' + 1; i <= 'Z'; i ++)
		res += abs(idx[i] - idx[i - 1]);
	
	cout << res << endl;

	return 0;
}

C - Max Ai+Bj

Problem Statement

You are given two integer sequences $A$ and $B$, each of length $N$. Choose integers $i,j$ $(1\le i,j\le N)$ to maximize the value of $A_i+B_j$.

Constraints

$1\le N\le 5\times 10^5$
$|A_i|\le 10^9$ $(i=1,2,\dots ,N)$
$|B_j|\le 10^9$ $(j=1,2,\dots ,N)$
All input values are integers.

Input

The input is given from Standard Input in the following format:

$N$
$A_1$ $A_2$ $\dots$ $A_N$
$B_1$ $B_2$ $\dots$ $B_N$

Output

Print the maximum possible value of $A_i+B_j$.

Sample Input 1

2
-1 5
3 -7

Sample Output 1

8

For $(i,j)=(1,1),(1,2),(2,1),(2,2)$, the values of A i + B j A_i + B_j Ai​<