project-euler/projectEuler020.cpp at master · perfectsimulation/project-euler · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
/*	Problem 20
	Factorial Digit Sum

	n! means n × (n − 1) × ... × 3 × 2 × 1

	For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800.
	The sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.

	Find the sum of the digits in the number 100!
*/

#include <iostream>
#include <string>

using namespace std;

int main () {
	int num [162] = { };
	int numTempOnes [162] = { };
	int numTempTens [162] = { };
	num [159] = 1;
	numTempOnes [159] = 1;
	numTempTens [159] = 1;

	for (int n = 99; n > 0; n--) {

		for (int index = 0; index < 162; index++) {
			numTempOnes [index] = num [index];
			numTempTens [index] = num [index];
		}

		string n_string = to_string (n);

		for (int digit = 0; digit <= n_string.length () - 1; digit++) {

			for (int index = 0; index < 162; index++) {

				if (num [index] != 0) {

					if (digit == 1) {
						int product = num [index] * int (n_string [digit] - 48);
						numTempOnes [index] = product;
					} else {
						if (n > 9) {
							int product = (num [index] * int (n_string [digit] - 48)) * 10;
							numTempTens [index] = product;
						} else {
							int product = num [index] * int (n_string [digit] - 48);
							numTempOnes [index] = product;
						}
					}

					if (numTempOnes [index] > 9 || numTempTens [index] > 9) {
						int multiDigitNums = 1;

						while (multiDigitNums != 0) {

							multiDigitNums = 0;

							for (int i = 0; i < 162; i++) {

								if (numTempOnes [i] > 9) {
									multiDigitNums++;
									string num_string = to_string (numTempOnes [i]);
									numTempOnes [i] = int (num_string [1] - 48);
									numTempOnes [i - 1] += int (num_string [0] - 48);
									break;
								}
							}

							for (int i = 0; i < 162; i++) {

								if (numTempTens [i] > 99) {
									multiDigitNums++;
									string num_string = to_string (numTempTens [i]);
									numTempTens [i] = int (num_string [2] - 48);
									numTempTens [i - 1] += int (num_string [1] - 48);
									numTempTens [i - 2] += int (num_string [0] - 48);
									break;

								} else if (numTempTens [i] > 9) {
									multiDigitNums++;
									string num_string = to_string (numTempTens [i]);
									numTempTens [i] = int (num_string [1] - 48);
									numTempTens [i - 1] += int (num_string [0] - 48);
									break;
								}
							}
						}
					}
				}
			}
		}

		for (int i = 0; i < 162; i++) {

			if (n > 9) {
				num [i] = numTempOnes [i] + numTempTens [i];
			} else {
				num [i] = numTempOnes [i];
			}

			int multiDigitNums = 1;

			while (multiDigitNums != 0) {

				multiDigitNums = 0;

				for (int i = 0; i < 162; i++) {

					if (num [i] > 99) {
						multiDigitNums++;
						string num_string = to_string (num [i]);
						num [i] = int (num_string [2] - 48);
						num [i - 1] += int (num_string [1] - 48);
						num [i - 2] += int (num_string [0] - 48);
						break;

					} else if (num [i] > 9) {
						multiDigitNums++;
						string num_string = to_string (num [i]);
						num [i] = int (num_string [1] - 48);
						num [i - 1] += int (num_string [0] - 48);
						break;
					}
				}
			}
		}
	}

	for (int i = 0; i < 161; i += 3) {
		cout << num [i] << num [i + 1] << num [i + 2] << " ";
	}

	int sumOf100factorial = 0;
	for (int i = 0; i < 162; i++) {
		sumOf100factorial += num [i];
	}

	cout << endl;
	cout << sumOf100factorial << endl;
}