You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 0134-gas-station.rs
    path of file: ./repos/NeetCode-Solutions/15_Greedy/04_Gas_Station
    
    the code of the file until where you have to start completion: /*
Problem: LeetCode 134 - Gas Station

Key Idea:
The key idea is to determine if there exists a starting gas station such that you can complete a circular tour of all gas stations.

Approach:
1. Initiali
    
    pub fn can_complete_circuit(gas: Vec<i32>, cost: Vec<i32>) -> i32 {
        let mut total_gas = 0;
        let mut current_gas = 0;
        let mut start_station = 0;

        for i in 0..gas.len() {
            let diff = gas[i] - cost[i];
            current_gas += diff;
            total_gas += diff;

            if current_gas < 0 {
                current_gas = 0;
                start_station = i + 1;
            }
        }

        if total_gas >= 0 {
            start_station as i32
        } else {
            -1
        }
    }