1. NPV
   • 1개년 50억, 2개년 60억, 3개년 70억의 예산을 가지고 NPV(순현재가치)가 가장 높아지는 안을 제시하시오

	1개년	2개년	3개년
1안	10	20	15
2안	15	14	19
3안	12	11	30
4안	13	25	20
5안	16	30	24

from itertools import combinations 
import pandas as pd 

investment_df = pd.DataFrame([[10, 20, 15],
                              [15, 14, 19], 
                              [12, 11, 30], 
                              [13, 25, 20], 
                              [16, 30, 24]], index=[1, 2, 3, 4, 5], columns=['yr1', 'yr2', 'yr3'])
investment_df

	yr1	yr2	yr3
1	10	20	15
2	15	14	19
3	12	11	30
4	13	25	20
5	16	30	24

items = [1, 2, 3, 4, 5]

combination_list = list(combinations(items, 2))+list(combinations(items, 3))

result_df = pd.DataFrame() 

for c in combination_list: 
    
    temp_df = pd.DataFrame()
    for item in items: 
        if item in c: 
            temp_df = pd.concat([temp_df, investment_df.loc[item]], axis=1) 
    
    result_df = pd.concat([result_df, temp_df.sum(axis=1)], axis=1)
    
result_df.columns = combination_list

df_t = result_df.T
df_t = df_t[(df_t['yr1'] < 50) & (df_t['yr2'] < 60) & (df_t['yr3'] < 70)]
df_t['total'] = df_t.sum(axis=1)
df_t.sort_values(by='total', ascending=False)

	yr1	yr2	yr3	total
(2, 3, 4)	40	50	69	159
(1, 3, 4)	35	56	65	156
(1, 2, 4)	38	59	54	151
(1, 2, 3)	37	45	64	146
(4, 5)	29	55	44	128
(3, 5)	28	41	54	123
(2, 5)	31	44	43	118
(1, 5)	26	50	39	115
(3, 4)	25	36	50	111
(2, 4)	28	39	39	106
(1, 4)	23	45	35	103
(2, 3)	27	25	49	101
(1, 3)	22	31	45	98
(1, 2)	25	34	34	93