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
|
// 76. Minimum Window Substring
#include "leetcode.h"
/*
* given two strings 's' and 't' of length 'n' and 'm' respectively, return the
* minimum window substring of 's' such that every character in 't' (including
* duplicates) is included in the window. if there is no such substring, return
* the empty string. the testcases will be generated such that the answer is
* unique.
*/
char *minWindow(char *s, char *t) {
int m = strlen(s), n = strlen(t), min = INT_MAX, l = -1, r, match = 0,
a_idx = -1, r_key, l_key;
int *alpha = calloc(52, sizeof(int));
int *alpha_copy = calloc(52, sizeof(int));
for (int i = 0; i < n; i++)
(t[i] >= 'a') ? alpha[t[i] - 'a']++ : alpha[t[i] - 'A' + 26]++;
for (r = 0; r < m; r++) {
r_key = (s[r] >= 'a') ? r_key = s[r] - 'a' : s[r] - 'A' + 26;
if (alpha[r_key]) {
if (l == -1)
l = r;
alpha_copy[r_key]++;
if (alpha_copy[r_key] <= alpha[r_key]) {
match++;
if (match == n) {
l_key = (s[l] >= 'a') ? s[l] - 'a' : s[l] - 'A' + 26;
while (match == n || !alpha[l_key]) {
if (alpha[l_key]) {
alpha_copy[l_key]--;
if (alpha_copy[l_key] < alpha[l_key]) {
if ((r - l + 1) < min) {
min = r - l + 1;
a_idx = l;
}
match--;
}
}
l++;
if (l < m)
l_key = (s[l] >= 'a') ? s[l] - 'a' : s[l] - 'A' + 26;
else
break;
}
}
}
}
}
if (a_idx == -1)
return "";
char *ans = malloc((min + 1) * sizeof(char));
ans[min] = '\0';
strncpy(ans, &s[a_idx], min);
return ans;
}
int main() {
char *s1 = "ADOBECODEBANC", *t1 = "ABC";
char *s2 = "a", *t2 = "a";
char *s3 = "a", *t3 = "aa";
printf("%s\n", minWindow(s1, t1)); // expect: BANC
printf("%s\n", minWindow(s2, t2)); // expect: a
printf("%s\n", minWindow(s3, t3)); // expect: null
}
|