• Small knowledge, big challenge! This article is participating in the creation activity of “Essential Tips for Programmers”.

Thank you very much for reading this article. Welcome [👍 like] [⭐ collect] [📝 comment] ~ Give up is not difficult, But insists it must be very cool ~ hope we all can be a little bit of progress every day ~ in this paper, from two headed white hat original ~ https://juejin.cn/user/2771185768884824/posts blog

2011. Variable values after operation:

There is a programming language that supports only four operations and one variable X:

Plus plus X and X++ add 1 to the value of the variable X– X and X– subtract 1 from the value of the variable X originally, X was 0

You’re given an array of strings called operations, which is a list of operations that return the final value of X after all the operations have been performed.

Sample 1

Input: operations = ["--X","X++","X++"] Output: 1 Explanation: The operation is performed as follows: Initially, X = 0 --X: X minus 1, X = 0-1 = -1 X++ : X++ : X+ 1, X = 0 + 1 = 1Copy the code

The sample 2

Input: operations = ["++X","++X","X++"] Output: 3 Explanation: The operations are performed as follows: Initially, X = 0 ++X: X+ 1, X = 0 + 1 = 1 ++X: X++ : X+ 1, X = 2 + 1 = 3Copy the code

Sample 3

Input: operations = ["X++","++X","--X","X--"] Output: 0 Explanation: The operations are performed as follows: Initially, X = 0 X++ : X plus 1, X = 0 + 1 = 1 ++X: X + 1, X = 1 + 1 = 2 --X: X minus 1, X = 2-1 = 1 --X: X minus 1, X = 1-1 = 0Copy the code

prompt

• 1 <= operations.length <= 100
• Operations [I] will be “++X”, “X++”, “–X”, or “X–“

Analysis of the

• There are four operation symbols, but only two operations. We want “++X”, “X++” as addition, “–X” or “X–” as subtraction. The intuitive way is to go to map, switch, if else, whatever.
• Each operation symbol is three characters, with an X at the beginning or the end, but only two characters in the middle, namely ‘+’ and ‘-‘.

Answer key

java

class Solution {
    public int finalValueAfterOperations(String[] operations) {
        int ans = 0;

        for (String operation : operations) {
            // Operation type
            char op = operation.charAt(1);
            switch (op) {
                case '+':
                    ans++;
                    break;
                case The '-':
                    ans--;
                    break; }}returnans; }}Copy the code

c

int finalValueAfterOperations(char ** operations, int operationsSize){
    int ans = 0;

    for (int i = 0; i < operationsSize; ++i) {
        char op = operations[i][1];
        switch (op) {
            case '+':
                ++ans;
                break;
            case The '-':
                --ans;
                break; }}return ans;
}
Copy the code

c++

class Solution {
public:
    int finalValueAfterOperations(vector<string>& operations) {
        int ans = 0;

        for (auto &operation : operations) {
            char op = operation[1];
            switch (op) {
                case '+':
                    ++ans;
                    break;
                case The '-':
                    --ans;
                    break; }}returnans; }};Copy the code

python

class Solution:
    def finalValueAfterOperations(self, operations: List[str]) - >int:
        ans = 0
        for operation in operations:
            if operation[1] = ='+':
                ans += 1
            else:
                ans -= 1
        return ans
Copy the code

go

func finalValueAfterOperations(operations []string) int {
    ans := 0
	for _, operation := range operations {
		op := operation[1]
		switch op {
		case '+':
			ans++
		case The '-':
			ans--
		}
	}
	return ans
}
Copy the code

rust

impl Solution {
    pub fn final_value_after_operations(operations: Vec<String- > >)i32 {
        operations.iter().map(|operation| {
            if operation.contains('+') {
                1
            } else{-1
            }
        }).sum()
    }
}
Copy the code

Original topic portal