36 lines
859 B
Java
36 lines
859 B
Java
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import java.util.Stack;
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class Solution {
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private record StackEntry(int count, StringBuilder str) {
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@Override
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public String toString() {
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return new StringBuilder().repeat(str(), count()).toString();
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}
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}
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public String decodeString(String s) {
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var stack = new Stack<StackEntry>();
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stack.push(new StackEntry(1, new StringBuilder()));
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int count = 0;
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for (int i = 0; i < s.length(); ++i) {
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var c = s.charAt(i);
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if (c == '[') {
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stack.push(new StackEntry(count, new StringBuilder()));
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count = 0;
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} else if (c == ']') {
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var last = stack.pop();
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stack.peek().str().append(last);
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} else if (Character.isDigit(c)) {
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count *= 10;
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count += c - '0';
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} else {
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stack.peek().str().append(c);
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}
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}
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return stack.pop().toString();
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}
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}
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