Decode String
~3 mins read
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def decodeString(self, s):
"""
s = "3[a]2[bc]", return "aaabcbc".
s = "3[a2[c]]", return "accaccacc".
s = "2[abc]3[cd]ef", return "abcabccdcdcdef".
"""
stack = []
coeff = 0
current_str = ""
for c in s:
if c.isdigit():
coeff = coeff * 10 + int(c)
elif c == "[":
stack.append((current_str, coeff))
current_str = ""
coeff = 0
elif c == "]":
prev_str, coeff = stack.pop()
current_str = prevString + num * current_str
else:
current_str += c
return current_str
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public class Solution {
public string DecodeString(string s) {
Stack<(string, int)> stack = new Stack<(string, int)>();
int coeff = 0;
string currentStr = "";
foreach (char c in s) {
if (char.IsDigit(c)) {
coeff = coeff * 10 + (c - '0');
} else if (c == '[') {
stack.Push((currentStr, coeff));
currentStr = "";
coeff = 0;
} else if (c == ']') {
var (prevStr, num) = stack.Pop();
var repeated = Enumerable.Repeat(currentStr, num)
currentStr = prevStr + string.Concat(repeated);
} else {
currentStr += c;
}
}
return currentStr;
}
}