解1:动态规划
// @lc code=start
/**
* @param {string} s
* @return {number}
*/
var longestValidParentheses = function(s) {
const sLen = s.length;
if (!sLen) return 0;
let dp = new Array(sLen).fill(0);
dp[-1] = 0;
s.split('').forEach((val, i) => {
let j = i - dp[i - 1] - 1;
if (val == ')' && j >= 0 && s[j] == '(') {
dp[i] = dp[i - 1] + dp[j - 1] + 2;
}
});
return Math.max(...dp);
};
console.log(longestValidParentheses("()(())")); // 6
// @lc code=end
解2:栈
var longestValidParentheses = function(s) {
let stack = [-1];
let len = 0;
let maxLen = 0;
s.split('').forEach((val, i) => {
if (val == '(') {
stack.push(i);
} else {
stack.pop();
if (stack.length == 0) {
stack.push(i);
} else {
len = i - stack[stack.length - 1];
maxLen = Math.max(len, maxLen);
}
}
});
return maxLen;
};
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