leetcode-java/src/ValidParenthesisString678.java at master · fluency03/leetcode-java · GitHub

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/**
 * Given a string containing only three types of characters: '(', ')' and '*',
 * write a function to check whether this string is valid. We define the
 * validity of a string by these rules:
 *
 * Any left parenthesis '(' must have a corresponding right parenthesis ')'.
 * Any right parenthesis ')' must have a corresponding left parenthesis '('.
 * Left parenthesis '(' must go before the corresponding right parenthesis ')'.
 * '*' could be treated as a single right parenthesis ')' or a single left parenthesis '(' or an empty string.
 * An empty string is also valid.
 *
 * Example 1:
 * Input: "()"
 * Output: True
 *
 * Example 2:
 * Input: "(*)"
 * Output: True
 *
 * Example 3:
 * Input: "(*))"
 * Output: True
 *
 * Note:
 * The string size will be in the range [1, 100].
 */

publicclassValidParenthesisString678 {
publicbooleancheckValidString(Strings) {
returncheckValidString(s.toCharArray(), 0, newint[]{0});
 }

publicbooleancheckValidString(char[] chars, inti, int[] count) {
if (i == chars.length) returncount[0] == 0;
charc = chars[i];
if (c == '(') {
count[0]++;
returncheckValidString(chars, i + 1, count);
 } elseif (c == ')') {
if (count[0] == 0) returnfalse;
count[0]--;
returncheckValidString(chars, i + 1, count);
 } else {
intpre = count[0];
if (checkValidString(chars, i + 1, count)) returntrue;
count[0] = pre + 1;
if (checkValidString(chars, i + 1, count)) returntrue;
count[0] = pre;
if (count[0] == 0) returnfalse;
count[0]--;
returncheckValidString(chars, i + 1, count);
 }
 }


/**
 * https://leetcode.com/problems/valid-parenthesis-string/solution/
 */
publicbooleancheckValidString2(Strings) {
intn = s.length();
if (n == 0) returntrue;
boolean[][] dp = newboolean[n][n];

for (inti = 0; i < n; i++) {
if (s.charAt(i) == '*') dp[i][i] = true;
if (i < n-1 &&
 (s.charAt(i) == '(' || s.charAt(i) == '*') &&
 (s.charAt(i+1) == ')' || s.charAt(i+1) == '*')) {
dp[i][i+1] = true;
 }
 }

for (intsize = 2; size < n; size++) {
for (inti = 0; i + size < n; i++) {
if (s.charAt(i) == '*' && dp[i+1][i+size] == true) {
dp[i][i+size] = true;
 } elseif (s.charAt(i) == '(' || s.charAt(i) == '*') {
for (intk = i+1; k <= i+size; k++) {
if ((s.charAt(k) == ')' || s.charAt(k) == '*') &&
 (k == i+1 || dp[i+1][k-1]) &&
 (k == i+size || dp[k+1][i+size])) {
dp[i][i+size] = true;
 }
 }
 }
 }
 }
returndp[0][n-1];
 }


/**
 * https://leetcode.com/problems/valid-parenthesis-string/solution/
 */
publicbooleancheckValidString3(Strings) {
intlo = 0, hi = 0;
for (charc: s.toCharArray()) {
lo += c == '(' ? 1 : -1;
hi += c != ')' ? 1 : -1;
if (hi < 0) break;
lo = Math.max(lo, 0);
 }
returnlo == 0;
 }

}