update code

data/3.算法高阶/1.leetcode/31_最长有效括号/solution.md

+# 最长有效括号
+以下错误的选项是？
+## aop
+### before
+```cpp
+
+```
+### after
+```cpp
+
+```
+
+## 答案
+```cpp
+class Solution
+{
+public:
+    int longestValidParentheses(string s)
+    {
+        int n = s.size();
+        if (n == 1)
+            return 0;
+        if (n == 2)
+        {
+            if (s[0] == '(' && s[1] == ')')
+                return 2;
+            else
+                return 0;
+        }
+
+        vector<int> dp(n, 0);
+        int max = 0;
+        for (int i = 1; i < n; i++)
+        {
+            if (s[i] == ')' && s[i - 1] == '(' && i >= 2)
+                dp[i] = dp[i - 2] + 2;
+            if (s[i] == ')' && s[i - 1] == '(' && i == 1)
+                dp[i] = 2;
+            if (s[i] == ')' && s[i - 1] == ')' && s[i - dp[i - 1] - 1] == '(')
+                dp[i] = dp[i - 1] + 2 + dp[dp[i - 1] - 2];
+            if (dp[i] > max)
+                max = dp[i];
+        }
+        return max;
+    }
+};
+```
+## 选项
+
+### A
+```cpp
+class Solution
+{
+public:
+    int longestValidParentheses(string s)
+    {
+        stack<int> stk;
+        int invalid = -1;
+        int len = 0, max_len = 0;
+        for (int i = 0; i < s.length(); i++)
+        {
+            if (s[i] == '(')
+            {
+                stk.push(i);
+            }
+            else
+            {
+                if (stk.empty())
+                {
+                    invalid = i;
+                }
+                else
+                {
+                    stk.pop();
+                    if (stk.empty())
+                    {
+                        max_len = max(i - invalid, max_len);
+                    }
+                    else
+                    {
+                        max_len = max(i - stk.top(), max_len);
+                    }
+                }
+            }
+        }
+        return max_len;
+    }
+};
+```
+
+### B
+```cpp
+class Solution
+{
+public:
+    int longestValidParentheses(string s)
+    {
+        stack<int> left;
+        left.push(-1);
+        int size = 0, maxSize = 0;
+        for (int i = 0; i < s.size(); i++)
+        {
+            if (s[i] == '(')
+                left.push(i);
+            else
+            {
+                if (left.size() != 1)
+                {
+                    left.pop();
+                    size = i - left.top();
+                    maxSize = max(maxSize, size);
+                }
+                else
+                {
+                    left.pop();
+                    left.push(i);
+                }
+            }
+        }
+        maxSize = max(maxSize, size);
+        return maxSize;
+    }
+};
+```
+
+### C
+```cpp
+class Solution
+{
+public:
+    int longestValidParentheses(string s)
+    {
+        queue<pair<int, int>> q;
+        bool *valid = new bool[s.length() + 1];
+        int imax = -1;
+        memset(valid, 0, sizeof(bool) * (s.length() + 1));
+        for (int i = 0; i < int(s.length()) - 1; i++)
+        {
+            if (s[i] == '(' && s[i + 1] == ')')
+            {
+                valid[i] = true;
+                valid[i + 1] = true;
+                q.push(make_pair(i, i + 1));
+            }
+        }
+        while (!q.empty())
+        {
+            pair<int, int> parentheses;
+            parentheses = q.front();
+            q.pop();
+            int l = parentheses.first, r = parentheses.second;
+            while (l >= 0 && valid[l])
+                l--;
+            while (r < s.length() && valid[r])
+                r++;
+            if (!valid[l] && !valid[r])
+            {
+                if (s[l] == '(' && s[r] == ')')
+                {
+                    valid[l] = true;
+                    valid[r] = true;
+                    q.push(make_pair(l, r));
+                }
+                else
+                {
+                    l = l + 1;
+                    r = r - 1;
+                }
+            }
+            if (r - l > imax)
+                imax = r - l;
+        }
+        return imax + 1;
+    }
+};
+
+```