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Commit 425b077

Browse files
Add C++ implementation
Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
1 parent b6d20d9 commit 425b077

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2 files changed

+69
-10
lines changed

2 files changed

+69
-10
lines changed

‎0127_word_ladder/word_ladder.c‎

Lines changed: 16 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,6 @@
11
#include <stdio.h>
22
#include <stdlib.h>
3+
#include <stdbool.h>
34
#include <string.h>
45

56
#define container_of(ptr, type, member) \
@@ -9,14 +10,10 @@
910
container_of(ptr, type, member)
1011

1112
#define list_first_entry(ptr, type, field) list_entry((ptr)->next, type, field)
12-
#define list_last_entry(ptr, type, field) list_entry((ptr)->prev, type, field)
1313

1414
#define list_for_each(p, head) \
1515
for (p = (head)->next; p != (head); p = p->next)
1616

17-
#define list_for_each_safe(p, n, head) \
18-
for (p = (head)->next, n = p->next; p != (head); p = n, n = p->next)
19-
2017
struct list_head {
2118
struct list_head *next, *prev;
2219
};
@@ -78,11 +75,11 @@ static int BKDRHash(char* str, int size)
7875
return hash % size;
7976
}
8077

81-
static struct word_node *find(char *word, struct list_head *hheads, int size)
78+
static struct word_node *find(char *word, struct list_head *dict, int size)
8279
{
8380
struct list_head *p;
8481
int hash = BKDRHash(word, size);
85-
list_for_each(p, &hheads[hash]) {
82+
list_for_each(p, &dict[hash]) {
8683
struct word_node *node = list_entry(p, struct word_node, node);
8784
if (node->step == 0 && !strcmp(node->word, word)) {
8885
return node;
@@ -98,18 +95,25 @@ static int ladderLength(char* beginWord, char* endWord, char** wordList, int wor
9895
struct list_head queue;
9996
struct word_node *node;
10097

101-
struct list_head *hheads = malloc(wordListSize * sizeof(*hheads));
98+
struct list_head *dict = malloc(wordListSize * sizeof(*dict));
10299
for (i = 0; i < wordListSize; i++) {
103-
INIT_LIST_HEAD(hheads + i);
100+
INIT_LIST_HEAD(dict + i);
104101
}
105102

106103
/* Add into hash list */
104+
bool found = false;
107105
for (i = 0; i < wordListSize; i++) {
108106
node = malloc(sizeof(*node));
109107
node->word = wordList[i];
110108
node->step = 0;
111109
int hash = BKDRHash(wordList[i], wordListSize);
112-
list_add(&node->node, &hheads[hash]);
110+
list_add(&node->node, &dict[hash]);
111+
if (!strcmp(endWord, wordList[i])) {
112+
found = true;
113+
}
114+
}
115+
if (!found) {
116+
return 0;
113117
}
114118

115119
/* FIFO */
@@ -127,8 +131,9 @@ static int ladderLength(char* beginWord, char* endWord, char** wordList, int wor
127131
for (c = 'a'; c <= 'z'; c++) {
128132
if (c == o) continue;
129133
word[i] = c;
130-
node = find(word, hheads, wordListSize);
134+
node = find(word, dict, wordListSize);
131135
if (node != NULL) {
136+
/* enqueue */
132137
list_add_tail(&node->link, &queue);
133138
node->step = first->step + 1;
134139
}
@@ -139,6 +144,7 @@ static int ladderLength(char* beginWord, char* endWord, char** wordList, int wor
139144
if (list_empty(&queue)) {
140145
return 0;
141146
} else {
147+
/* dequeue */
142148
first = list_first_entry(&queue, struct word_node, link);
143149
list_del(&first->link);
144150
}

‎0127_word_ladder/word_ladder.cc‎

Lines changed: 53 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,53 @@
1+
#include <bits/stdc++.h>
2+
3+
using namespace std;
4+
5+
class Solution {
6+
public:
7+
int ladderLength(string beginWord, string endWord, vector<string>& wordList) {
8+
unordered_set<string> dict(wordList.begin(), wordList.end());
9+
if (!dict.count(endWord)) {
10+
return 0;
11+
}
12+
13+
// double BFS
14+
int step = 1;
15+
unordered_set<string> s1, s2, tmp, visited;
16+
s1.insert(beginWord);
17+
s2.insert(endWord);
18+
while (!s1.empty() && !s2.empty()) {
19+
if (s1.size() > s2.size()) {
20+
tmp = s1;
21+
s1 = s2;
22+
s2 = tmp;
23+
}
24+
tmp.clear();
25+
26+
for (auto str : s1) {
27+
if (s2.count(str)) {
28+
return step;
29+
}
30+
if (!visited.count(str)) {
31+
visited.insert(str);
32+
}
33+
34+
for (int i = 0; i < str.length(); i++) {
35+
char o = str[i];
36+
for (char c = 'a'; c <= 'z'; c++) {
37+
if (c == o) continue;
38+
str[i] = c;
39+
if (dict.count(str) && !visited.count(str)) {
40+
tmp.insert(str);
41+
}
42+
}
43+
str[i] = o;
44+
}
45+
}
46+
47+
// update
48+
s1 = tmp;
49+
step++;
50+
}
51+
return 0;
52+
}
53+
};

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