Portfolio


function solution(numbers, target) {
    let answer = 0;
    dfs(0, 0);
    // 재귀함수를 이용한 DFS
    function dfs(index, sum) {
        if(index === numbers.length) {
            if(sum === target) {
                answer++;
            }
            return;
        }
        dfs(index + 1, sum + numbers[index]);
        dfs(index + 1, sum - numbers[index]);
    }
    
    return answer;
}


function solution(numbers, target) {
    var answer = 0;
    
    function dfs(arr,result) {
        if (arr.length <= 0) {
            if (result === target) {
                answer++;
            }
            return;
        }
        
        dfs(arr.slice(1),result+arr[0]);
        dfs(arr.slice(1),result-arr[0]);
    }
    
    dfs(numbers,0);
    
    return answer;
}


function solution(numbers, target) {
    //음이 아닌 정수 n개
    //입력값이 매우 작음 - numbers.length가 최대 20
    //각 수가 +를 가지냐 or -를 가져야되냐
    let result = 0
    function dfs(count,acc){
        if(count >= numbers.length){
            if(acc === target){
                result ++
            }
            return}
            dfs(count+1,acc+numbers[count])
            dfs(count+1,acc-numbers[count])
    // 1+1+1+1+1 
    // - 리턴 후 1+1+1+1-1 .... 이런식
    }
    dfs(0,0)
    return result
}


function solution(numbers, target) {
    let count = 0
    const stack = [[numbers[0],0],[-numbers[0], 0]]
    
    while(stack.length>0){
        let [currentValue,currentIdx] = stack.pop()
        const nextIdx = currentIdx+1
        
        if(currentIdx===numbers.length-1 && currentValue===target){
            count++
        }else if(currentIdx<numbers.length-1){
            stack.push([currentValue+numbers[nextIdx],currentIdx+1])
            stack.push([currentValue-numbers[nextIdx],currentIdx+1])
        }
    }
    return count
}