Codeforces 431A Black Square Solution & Explanation

Difficulty : 800

Problem Description

Quite recently, a very smart student named Jury decided that lectures are boring, so he downloaded a game called “Black Square” on his super cool touchscreen phone.

In this game, the phone’s screen is divided into four vertical strips. Each second, a black square appears on some of the strips. According to the rules of the game, Jury must use this second to touch the corresponding strip to make the square go away. As Jury is both smart and lazy, he counted that he wastes exactly a_i calories on touching the i-th strip.

You’ve got a string s, describing the process of the game and numbers a₁, a₂, a₃, a₄. Calculate how many calories Jury needs to destroy all the squares?

Input

The first line contains four space-separated integers a₁, a₂, a₃, a₄ (0 ≤ a₁, a₂, a₃, a₄ ≤ 10⁴).

The second line contains string s (1 ≤ |s| ≤ 10⁵), where the і-th character of the string equals “1”, if on the i-th second of the game the square appears on the first strip, “2”, if it appears on the second strip, “3”, if it appears on the third strip, “4”, if it appears on the fourth strip.

Output

Print a single integer — the total number of calories that Jury wastes.

Examples

Solution

In this problem, we can subtract 1 from each number in the second line of input to search in the array formed by the first line. (Because arrays start from 0.)

C# Solution

Solution1

int[] arr = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
int[] arr2 = Console.ReadLine().Select(c => int.Parse(c.ToString())).ToArray();

int res = 0;
foreach(var dtl in arr2){
    res+=arr[dtl-1];    //index start from 0
}

Console.WriteLine(res);

Conclusion

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The problem link : Problem – 431A – Codeforces

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