def find_maxima(x):
    """Find local maxima of x.

    Input arguments:
    x -- 1D list of real numbers

    Output:
    idx -- list of indices of the local maxima in x
    """
    idx = []
    for i in range(len(x)):
        if i == 0 and x[i] > x[i+1]:
            idx.append(i)
        elif i != len(x)-1 and x[i] > x[i-1] and x[i] > x[i+1]:
            idx.append(i)
        elif i== len(x)-1 and x[i] > x[i-1]:
            idx.append(i)    
    return idx


if __name__ == "__main__":
    x = [1, 2, 3]
    # x = [1,2,2,3,1]
    print(find_maxima(x))