import time

def search(L, value):
    '''Return the index of value in L, or len(L) if value doesn't
    exist in L.'''
    i = 0  # The current index in L.
    while i < len(L) and L[i] != value:
        i += 1

    return i

def sentinel_search(L, value):
    '''Return the index of value in L, or len(L) if value doesn't
    exist in L.'''
    L.append(value)
    i = 0  # The current index in L.
    while L[i] != value:
        i += 1
    L.pop()
    return i

def binary_search(L,v):
    """Return the index of the leftmost occurrence of v in list L, or -1 if
    v is not in L."""

    i = 0
    j = len(L) - 1
    while i != j + 1:
        m = (i + j) / 2
        if L[m] == v:
            print m
            return m
        elif L[m] < v:
            i = m + 1
        else:
            j = m - 1

    if 0 <= i < len(L) and L[i] == v:
        return i
    else:
        return -1

if __name__ == "__main__":
    L = range(1000000)
    
    t1 = time.time()
    print sentinel_search(L, 999999),'sb 999999'
    t2 = time.time()
    print "sentinel search:", t2 - t1
    
    t1 = time.time()
    print search(L, 999999), 'sb 999999'
    t2 = time.time()
    print "search:", t2 - t1

    t1 = time.time()
    print binary_search(L, 999999), 'sb 999999'
    t2 = time.time()
    print "binary search:", t2 - t1