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32.java
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32.java
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__________________________________________________________________________________________________
1ms
class Solution {
public int longestValidParentheses(String s) {
int l = 0;
int r = 0;
int ans = 0;
for (int i = 0; i < s.length(); i++) {
if (s.charAt(i) == '(') {
l++;
} else {
r++;
}
if (r == l) {
ans = Math.max(ans, r * 2);
} else if (r > l) {
l = 0;
r = 0;
}
}
l = 0;
r = 0;
for (int i = s.length() - 1; i >= 0; i--) {
if (s.charAt(i) == '(') {
l++;
} else {
r++;
}
if (r == l) {
ans = Math.max(ans, l * 2);
} else if (l > r) {
l = 0;
r = 0;
}
}
return ans;
}
}
__________________________________________________________________________________________________
1ms
public class Solution {
public int longestValidParentheses(String s) {
int length=s.length();
if (length==0) {
return 0;
}
int ans=0;
char[] c=s.toCharArray();
int[] vals=new int[length];
for (int i = length-2; i >= 0; i--) {
if (c[i]=='(') {
int t=i+1+vals[i+1];
if (t<length&&c[t]==')') {
vals[i]=vals[i+1]+2;
vals[i]+=((t+1<length)?vals[t+1]:0);
ans=ans<vals[i]?vals[i]:ans;
}
}
}
return ans;
}
}
__________________________________________________________________________________________________
2ms
class Solution {
public int longestValidParentheses(String s) {
if (s.length() <= 1) return 0; // 单个char也不能组成valid parentheses
int[] dp = new int[s.length()];
int max = Integer.MIN_VALUE;
for (int i = 1; i < s.length(); i++) {
if (s.charAt(i) == '(') {
dp[i] = 0;
} else if (s.charAt(i) == ')') {
if (s.charAt(i - 1) == '(') {
dp[i] = i - 2 >= 0 ? dp[i - 2] + 2 : 2;
} else if (s.charAt(i - 1) == ')') {
if (i - dp[i - 1] - 1 >= 0 && s.charAt(i - dp[i - 1] - 1) == '(') {
dp[i] = i - dp[i - 1] - 2 >= 0 ? dp[i - 1] + 2 + dp[i - dp[i - 1] - 2] : dp[i - 1] + 2;
}
}
} else throw new IllegalArgumentException("invlid input!");
max = Math.max(max, dp[i]);
}
return max;
}
}
__________________________________________________________________________________________________
35368 kb
class Solution {
public int longestValidParentheses(String s) {
int left = 0, right = 0, maxlength = 0;
for (int i = 0; i < s.length(); i++){
if (s.charAt(i)=='(') {
left ++;
} else {
right++;
}
if (left == right ){
maxlength = Math.max(maxlength, right * 2);
}else if (right > left ) {
left = right = 0;
}
}
left = right = 0;
for (int i=s.length()-1; i>=0; i--){
if ( s.charAt(i) == ')') {
right ++;
}else
left ++;
if (left == right ){
maxlength = Math.max(maxlength,left*2);
} else if (left > right) {
left = right = 0;
}
}
return maxlength;
}
}
__________________________________________________________________________________________________
35428 kb
class Solution {
public int longestValidParentheses(String s) {
Stack<Integer> stack = new Stack<Integer>();
stack.push(-1);
int max = 0;
for (int i=0;i<s.length();i++) {
if (s.charAt(i) == '(') {
stack.push(i);
} else {
stack.pop();
if (stack.isEmpty()) {
stack.push(i);
} else {
max = Math.max(max, i - stack.peek());
}
}
}
return max;
}
}
__________________________________________________________________________________________________