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31 lines
605 B
31 lines
605 B
package class28;
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public class Problem_0020_ValidParentheses {
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public static boolean isValid(String s) {
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if (s == null || s.length() == 0) {
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return true;
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}
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char[] str = s.toCharArray();
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int N = str.length;
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char[] stack = new char[N];
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int size = 0;
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for (int i = 0; i < N; i++) {
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char cha = str[i];
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if (cha == '(' || cha == '[' || cha == '{') {
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stack[size++] = cha == '(' ? ')' : (cha == '[' ? ']' : '}');
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} else {
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if (size == 0) {
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return false;
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}
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char last = stack[--size];
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if (cha != last) {
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return false;
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}
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}
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}
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return size == 0;
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}
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}
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