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
143
144
|
/*
Challenge 100
TASK #2 > Triangle Sum
Submitted by: Mohammad S Anwar
You are given triangle array.
Write a script to find the minimum path sum from top to bottom.
When you are on index i on the current row then you may move to either
index i or index i + 1 on the next row.
Example 1:
Input: Triangle = [ [1], [2,4], [6,4,9], [5,1,7,2] ]
Output: 8
Explanation: The given triangle
1
2 4
6 4 9
5 1 7 2
The minimum path sum from top to bottom: 1 + 2 + 4 + 1 = 8
[1]
[2] 4
6 [4] 9
5 [1] 7 2
Example 2:
Input: Triangle = [ [3], [3,1], [5,2,3], [4,3,1,3] ]
Output: 7
Explanation: The given triangle
3
3 1
5 2 3
4 3 1 3
The minimum path sum from top to bottom: 3 + 1 + 2 + 1 = 7
[3]
3 [1]
5 [2] 3
4 3 [1] 3
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <ctype.h>
#define MIN(a,b) ((a)<(b)?(a):(b))
// memory allocation
void* check_mem(void* p) {
if (!p) {
fputs("Out of memory", stderr);
exit(EXIT_FAILURE);
}
return p;
}
// triangle (stored as a square)
typedef struct {
int rows;
int** data;
} Triangle;
Triangle* triangle_new(void) {
Triangle* triangle = check_mem(calloc(1, sizeof(Triangle)));
return triangle;
}
void triangle_free(Triangle* triangle) {
for (int i = 0; i < triangle->rows; i++)
free(triangle->data[i]);
free(triangle->data);
free(triangle);
}
void triangle_add_row(Triangle* triangle) {
triangle->rows++;
triangle->data = check_mem(realloc(triangle->data,
triangle->rows * sizeof(int*)));
triangle->data[triangle->rows - 1] = NULL;
for (int i = 0; i < triangle->rows; i++)
triangle->data[i] = check_mem(realloc(triangle->data[i],
triangle->rows * sizeof(int)));
}
bool triangle_parse_row(Triangle* triangle, int row, const char* text) {
assert(row >= 0 && row < triangle->rows);
for (int i = 0; i < triangle->rows; i++) {
while (*text && !isdigit(*text)) text++;
if (!isdigit(*text))
return false;
triangle->data[row][i] = atoi(text);
while (*text && isdigit(*text)) text++;
}
return true;
}
bool triangle_parse(Triangle* triangle, int argc, char* argv[]) {
for (int row = 0; row < argc; row++) {
triangle_add_row(triangle);
if (!triangle_parse_row(triangle, row,argv[row]))
return false;
}
return true;
}
int triangle_min_sum_1(Triangle* triangle, int sum, int row, int col) {
sum += triangle->data[row][col];
if (row + 1 == triangle->rows)
return sum;
else {
int sum1 = triangle_min_sum_1(triangle, sum, row + 1, col);
int sum2 = triangle_min_sum_1(triangle, sum, row + 1, col + 1);
return MIN(sum1, sum2);
}
}
int triangle_min_sum(Triangle* triangle) {
return triangle_min_sum_1(triangle, 0, 0, 0);
}
int main(int argc, char* argv[]) {
if (argc == 1) {
fputs("Usage: ch-2 row row ...", stderr);
return EXIT_FAILURE;
}
argc--; argv++;
Triangle* triangle = triangle_new();
if (!triangle_parse(triangle, argc, argv)) {
fputs("Malformed triangle", stderr);
return EXIT_FAILURE;
}
int sum = triangle_min_sum(triangle);
printf("%d\n", sum);
triangle_free(triangle);
}
|
