leetcode/src/s0032_longest_valid_parentheses.cpp

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#include "s0032_longest_valid_parentheses.hpp"
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int S0032::longestValidParentheses(string s) {
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int maxans = 0, n = s.length();
vector<int> dp(n, 0);
for (int i = 1; i < n; i++) {
if (s[i] == ')') {
if (s[i - 1] == '(') {
dp[i] = (i >= 2 ? dp[i - 2] : 0) + 2;
} else if (i - dp[i - 1] > 0 && s[i - dp[i - 1] - 1] == '(') {
dp[i] =
dp[i - 1] + ((i - dp[i - 1]) >= 2 ? dp[i - dp[i - 1] - 2] : 0) + 2;
}
maxans = max(maxans, dp[i]);
}
}
return maxans;
}