[JavaScript]プログラマーブリッジを通るトラックLEVEL 2

function solution(bridge_length, weight, truck_weights) {
    let answer = 1;
    let trucks = [...truck_weights];
    let ing = [[trucks.shift(), 0]];
    
    while (ing.length > 0) {
        for (let i=0; i<ing.length; i++) {
            ing[i][1]++;
        }
        
        if (ing[0][1] >= bridge_length) ing.shift();
        
        const sum = ing.reduce((a, b) => a + b[0], 0);
        if (trucks.length > 0 && sum + trucks[0] <= weight) ing.push([trucks.shift(), 0]);
        
        answer++;
    }
    
    return answer;
}