Created
November 10, 2017 01:34
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Leetcode 10 - pass online judge - Nov. 9, need to remove redundant code, "matching one time at least" branch precedes "match zero time" to avoid timeout.
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using System; | |
class Solution | |
{ | |
public static bool isMatchHelper(string text, string pattern, int textIndex, int patternIndex) // abbb, ab* | |
{ | |
var lengthText = text.Length; | |
var lengthPattern = pattern.Length; | |
// base case | |
if (patternIndex == lengthPattern) | |
{ | |
return lengthText == textIndex; | |
} | |
var template = pattern[patternIndex]; //'a' | |
var isContainingStar = template != '*' && patternIndex < lengthPattern - 1 && pattern[patternIndex + 1] == '*'; // standalone "*" | |
// base case - text string is empty but pattern string not emtpy | |
if ((lengthText == 0 || lengthText == textIndex) && isContainingStar) | |
{ | |
return isMatchHelper(text, pattern, textIndex, patternIndex + 2); | |
} | |
if (lengthText == textIndex) | |
{ | |
return false; | |
} | |
// pattenrIndex < lengthPattern | |
// single char match | |
var visit = text[textIndex]; // out-of-index range // 'a' | |
if (!isContainingStar) | |
{ | |
var comparisonEqual = visit == template || template == '.'; | |
if (!comparisonEqual) | |
{ | |
return false; | |
} | |
return isMatchHelper(text, pattern, textIndex + 1, patternIndex + 1); | |
} | |
var matchingFirstChar = visit == template || template == '.'; | |
return ( matchingFirstChar && isMatchHelper(text, pattern, textIndex + 1, patternIndex)) || // match 1 time at least | |
isMatchHelper(text, pattern, textIndex, patternIndex + 2); // match 0 time | |
} | |
static void Main(string[] args) | |
{ | |
Console.WriteLine(IsMatch("bbbba",".*a*a")); | |
} | |
} |
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