binary search 를 응용한 주어진 값의 인덱스 찾기

gistfile1.txt

int findNeedle(int input[], int start, int end, int needle) {
    if(start > end) return -1;
    
    int mid = floor((start+end)/2);
    int result;
    
    if(input[mid] == needle) return mid;
    else if(input[mid] < needle) {
        result = findNeedle(input, mid+1, end, needle);
        if(result == -1) {
            return end+1;
        }
    }
    else {
        result = findNeedle(input, start, mid-1, needle);
        if(result == -1) {
            return start;
        }
    }

}