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feat: add Longest Valid Parentheses LeetCode problem (#1166)

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Co-authored-by: David Leal <halfpacho@gmail.com>
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Alexander Pantyukhin 2022-12-17 01:37:54 +04:00 committed by GitHub
parent 1d4ccc39a9
commit 8992d267ac
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1
leetcode/DIRECTORY.md
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@ -24,6 +24,7 @@
| 27 | [Remove Element](https://leetcode.com/problems/remove-element/) | [C](./src/27.c) | Easy |
| 28 | [Implement strStr()](https://leetcode.com/problems/implement-strstr/) | [C](./src/28.c) | Easy |
| 29 | [Divide Two Integers](https://leetcode.com/problems/divide-two-integers/) | [C](./src/29.c) | Medium |
| 32 | [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses/) | [C](./src/32.c) | Hard |
| 35 | [Search Insert Position](https://leetcode.com/problems/search-insert-position/) | [C](./src/35.c) | Easy |
| 38 | [Count and Say](https://leetcode.com/problems/count-and-say/) | [C](./src/38.c) | Easy |
| 42 | [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water/) | [C](./src/42.c) | Hard |

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leetcode/src/32.c Normal file
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#define max(x,y)(((x)>(y))?(x):(y))
const int notCalculated = -2;
const int notValid = -1;
int getEndValidIndexFromDp(int* dp, char* s, int index, int lenS){
if (index >= lenS){
return notValid;
}
if (dp[index] == notCalculated){
dp[index] = getEndValidIndex(dp, s, index, lenS);
}
return dp[index];
}
int getEndValidIndex(int* dp, char* s, int index, int lenS){
if (s[index] == '('){
if (index + 1 >= lenS){
return notValid;
}
if (s[index + 1] == ')'){
return max(index + 1, getEndValidIndexFromDp(dp, s, index + 2, lenS));
}
int nextEndValidIndex = getEndValidIndexFromDp(dp, s, index + 1, lenS);
if (nextEndValidIndex == notValid || nextEndValidIndex + 1 >= lenS || s[nextEndValidIndex + 1] != ')') {
return notValid;
}
return max(nextEndValidIndex + 1, getEndValidIndexFromDp(dp, s, nextEndValidIndex + 2, lenS));
}
return notValid;
}
// Dynamic Programming. UP -> down approach.
// Runtime: O(n)
// Space: O(n)
int longestValidParentheses(char * s){
int lenS = strlen(s);
if (lenS == 0){
return 0;
}
int* dp = malloc(lenS * sizeof(int));
for(int i = 0; i < lenS; i++){
dp[i] = notCalculated;
}
int result = 0;
for(int i = 0; i < lenS; i++){
result = max(result, getEndValidIndexFromDp(dp, s, i, lenS) - i + 1);
}
free(dp);
return result;
}