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begeekmyfriendbegeekmyfriend
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Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
1 parent acdf017 commit 463ef54

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24 files changed

+213
-176
lines changed

24 files changed

+213
-176
lines changed

‎041_first_missing_positive/missing_positive.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,9 @@ static int firstMissingPositive(int* nums, int numsSize)
1616

1717
int i = 0;
1818
while (i < numsSize) {
19-
if (nums[i] != i + 1 && nums[i] > 0 && nums[i] <= numsSize && nums[i] != nums[nums[i] - 1]) {
19+
/* nums[i] should be i+1 and nums[nums[i] - 1] should be nums[i] */
20+
if (nums[i] != i + 1 && nums[i] > 0 && nums[i] <= numsSize && nums[nums[i] - 1] != nums[i]) {
21+
/* nums[nums[i] - 1] <- nums[i] */
2022
swap(nums + i, nums + nums[i] - 1);
2123
} else {
2224
i++;

‎045_jump_game_ii/jump_game.c

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,9 @@ static int jump(int* nums, int numsSize)
1212
int steps = 0;
1313
while (hi < numsSize - 1) {
1414
int right = 0;
15+
/* [lo, hi] is the next location range, find the farest jump */
1516
for (i = lo; i <= hi; i++) {
17+
/* Assume right > hi for the purpose of the problem */
1618
right = max(i + nums[i], right);
1719
}
1820
lo = hi + 1;

‎055_jump_game/jump_game.c

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@ static bool canJump(int* nums, int numsSize)
1414
if (pos < i || pos >= numsSize - 1) {
1515
break;
1616
}
17+
/* if all positive number it always can arrive. */
1718
pos = max(i + nums[i], pos);
1819
}
1920

‎075_sort_colors/sort_colors.c

Lines changed: 15 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -9,49 +9,38 @@ static inline void swap(int *a, int *b)
99
*b = tmp;
1010
}
1111

12-
/*
13-
* RED = 0
14-
* WHITE = 1
15-
* BLUE = 2
16-
*/
1712
static void sortColors(int* nums, int numsSize)
1813
{
19-
int i = 0, j = numsSize - 1;
20-
while (i < j) {
21-
while (nums[i] == 0 && i < j) {
22-
i++;
14+
int i, j = 0;
15+
for (i = 0; i < numsSize; i++) {
16+
if (nums[i] == 0) {
17+
swap(nums + j, nums + i);
18+
j++;
2319
}
24-
while (nums[j] != 0 && j > i) {
25-
j--;
26-
}
27-
swap(nums + i, nums + j);
2820
}
29-
j = numsSize - 1;
30-
while (i < j) {
31-
while (nums[i] == 1 && i < j) {
32-
i++;
33-
}
34-
while (nums[j] != 1 && j > i) {
35-
j--;
21+
22+
for (i = j; i < numsSize; i++) {
23+
if (nums[i] == 1) {
24+
swap(nums + j, nums + i);
25+
j++;
3626
}
37-
swap(nums + i, nums + j);
3827
}
3928
}
4029

4130
int main(int argc, char **argv)
4231
{
43-
if (argc != 2) {
44-
fprintf(stderr, "Usage: ./test colors\n");
32+
if (argc < 2) {
33+
fprintf(stderr, "Usage: ./test 2 0 2 1 1 0\n");
4534
exit(-1);
4635
}
47-
int i, count = strlen(argv[1]);
36+
int i, count = argc - 1;
4837
int *nums = malloc(count * sizeof(int));
4938
for (i = 0; i < count; i++) {
50-
nums[i] = argv[1][i] - '0';
39+
nums[i] = atoi(argv[i + 1]);
5140
}
5241
sortColors(nums, count);
5342
for (i = 0; i < count; i++) {
54-
printf("%d", nums[i]);
43+
printf("%d ", nums[i]);
5544
}
5645
printf("\n");
5746
return 0;

‎080_remove_duplicates_from_sorted_array_ii/rm_dups.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,14 +9,17 @@ static int removeDuplicates(int* nums, int numsSize)
99

1010
int i;
1111
int len = 0;
12-
int count = 0;
12+
int count = 1;
1313
for (i = 1; i < numsSize; i++) {
14+
/* Find the start position to be replaced */
1415
if (nums[len] == nums[i]) {
1516
if (count < 2) {
1617
count++;
18+
/* Replace in each iteration */
1719
nums[++len] = nums[i];
1820
}
1921
} else {
22+
/* Here there are more than 2 duplicates */
2023
count = 1;
2124
nums[++len] = nums[i];
2225
}

‎085_maximal_rectangle/maximal_rectangle.c

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -11,32 +11,32 @@ static inline int max(int a, int b)
1111
static int area_calc(int *heights, int size)
1212
{
1313
int *indexes = malloc(size * sizeof(int));
14-
int *left = malloc(size * sizeof(int));
15-
int *right = malloc(size * sizeof(int));
14+
int *lhist = malloc(size * sizeof(int));
15+
int *rhist = malloc(size * sizeof(int));
1616

1717
int i, pos = 0;
1818
for (i = 0; i < size; i++) {
19-
/* monotonous increasing stack */
19+
/* squeeze to keep monotonous increasing histograms */
2020
while (pos > 0 && heights[indexes[pos - 1]] >= heights[i]) {
2121
pos--;
2222
}
23-
left[i] = pos == 0 ? -1 : indexes[pos - 1];
23+
lhist[i] = pos == 0 ? -1 : indexes[pos - 1];
2424
indexes[pos++] = i;
2525
}
2626

2727
pos = 0;
2828
for (i = size - 1; i >= 0; i--) {
29-
/* monotonous increasing stack */
29+
/* squeeze to keep monotonous increasing histograms */
3030
while (pos > 0 && heights[indexes[pos - 1]] >= heights[i]) {
3131
pos--;
3232
}
33-
right[i] = pos == 0 ? size : indexes[pos - 1];
33+
rhist[i] = pos == 0 ? size : indexes[pos - 1];
3434
indexes[pos++] = i;
3535
}
3636

3737
int max_area = 0;
3838
for (i = 0; i < size; i++) {
39-
int area = heights[i] * (right[i] - left[i] - 1);
39+
int area = heights[i] * (rhist[i] - lhist[i] - 1);
4040
max_area = max(area, max_area);
4141
}
4242

‎086_partition_list/partition_list.c

Lines changed: 20 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -6,29 +6,37 @@ struct ListNode {
66
struct ListNode *next;
77
};
88

9-
struct ListNode* partition(struct ListNode* head, int x) {
9+
struct ListNode* partition(struct ListNode* head, int x)
10+
{
1011
struct ListNode dummy;
11-
struct ListNode *p = NULL, *start = &dummy, *pivot;
12+
struct ListNode *prev1 = &dummy, *pivot;
13+
1214
dummy.next = head;
1315
for (pivot = head; pivot != NULL; pivot = pivot->next) {
1416
if (pivot->val >= x) {
15-
/* start->next == pivot */
1617
break;
1718
}
18-
start = pivot;
19+
prev1 = pivot;
1920
}
2021

21-
struct ListNode *prev;
22-
for (p = pivot; p != NULL; p = p->next) {
22+
struct ListNode *p = pivot->next;
23+
struct ListNode *prev2 = pivot;
24+
while (p != NULL) {
2325
if (p->val < x) {
24-
prev->next = p->next;
25-
p->next = start->next;
26-
start->next = p;
27-
start = p;
28-
p = prev;
26+
/* deletion */
27+
prev2->next = p->next;
28+
/* insertion */
29+
p->next = prev1->next;
30+
prev1->next = p;
31+
/* iteration */
32+
prev1 = p;
33+
p = prev2->next;
34+
} else {
35+
prev2 = p;
36+
p = p->next;
2937
}
30-
prev = p;
3138
}
39+
3240
return dummy.next;
3341
}
3442

‎087_scramble_string/scramble_string.c

Lines changed: 2 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -12,25 +12,21 @@
1212
* or
1313
* isScramble(s1[0..j], s2[n - j - 1, n]) && isScramble(s1[j+1..n], s2[0..n - j])
1414
*/
15-
#define N 128
16-
1715
static bool scramble(char *s1, int low1, int high1, char *s2, int low2, int high2)
1816
{
1917
if (high1 - low1 != high2 - low2) {
2018
return false;
2119
} else if (!memcmp(s1 + low1, s2 + low2, high1 - low1 + 1)) {
2220
return true;
2321
} else {
24-
int i, c1[N], c2[N];
25-
memset(c1, 0, N * sizeof(int));
26-
memset(c2, 0, N * sizeof(int));
22+
int i, c1[128] = { 0 }, c2[128] = { 0 };
2723
for (i = low1; i <= high1; i++) {
2824
c1[s1[i]]++;
2925
}
3026
for (i = low2; i <= high2; i++) {
3127
c2[s2[i]]++;
3228
}
33-
if (memcmp(c1, c2, N * sizeof(int))) {
29+
if (memcmp(c1, c2, 128 * sizeof(int))) {
3430
return false;
3531
} else {
3632
int len = high1 - low1 + 1;

‎094_binary_tree_inorder_traversal/bst_inorder_traversal.c

Lines changed: 10 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1,24 +1,22 @@
11
#include <stdio.h>
22
#include <stdlib.h>
33

4-
struct TreeNode {
5-
int val;
6-
struct TreeNode *left;
7-
struct TreeNode *right;
8-
};
4+
struct TreeNode {
5+
int val;
6+
struct TreeNode *left;
7+
struct TreeNode *right;
8+
};
99

1010
static void traverse(struct TreeNode *node, int *result, int *count)
1111
{
12-
if (node->left != NULL) {
13-
traverse(node->left, result, count);
12+
if (node == NULL) {
13+
return;
1414
}
15-
15+
16+
traverse(node->left, result, count);
1617
result[*count] = node->val;
1718
(*count)++;
18-
19-
if (node->right != NULL) {
20-
traverse(node->right, result, count);
21-
}
19+
traverse(node->right, result, count);
2220
}
2321

2422
/**

‎113_path_sum_ii/path_sum.c

Lines changed: 5 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -12,20 +12,17 @@ static void dfs(struct TreeNode *node, int sum, int *stack, int len, int **resul
1212
{
1313
if (node == NULL) {
1414
return;
15-
}
16-
17-
sum -= node->val;
18-
if (node->left == NULL && node->right == NULL && sum == 0) {
15+
} else if (node->left == NULL && node->right == NULL && sum == node->val) {
1916
results[*count] = malloc((len + 1) * sizeof(int));
2017
memcpy(results[*count], stack, len * sizeof(int));
2118
results[*count][len] = node->val;
2219
sizes[*count] = len + 1;
2320
(*count)++;
24-
return;
21+
} else {
22+
stack[len] = node->val;
23+
dfs(node->left, sum - node->val, stack, len + 1, results, sizes, count);
24+
dfs(node->right, sum - node->val, stack, len + 1, results, sizes, count);
2525
}
26-
stack[len] = node->val;
27-
dfs(node->left, sum, stack, len + 1, results, sizes, count);
28-
dfs(node->right, sum, stack, len + 1, results, sizes, count);
2926
}
3027

3128
static int **pathSum(struct TreeNode *root, int sum, int **columnSizes, int *returnSize)

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