■ 조합을 구하는 방법을 보여준다.
▶ 조합 구하기 예제 (C#)
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using System; long combination = GetCombination(3, 2); Console.WriteLine(combination); |
▶ 조합 구하기 (C#)
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#region 조합 구하기 - GetCombination(totalCount, extractionCount) /// <summary> /// 조합 구하기 /// </summary> /// <param name="totalCount">전체 수</param> /// <param name="extractionCount">추출 수</param> /// <returns>조합</returns> public long GetCombination(int totalCount, int extractionCount) { return GetPermutation(totalCount, extractionCount) / GetFactorial(extractionCount); } #endregion #region 팩토리얼 분할 구하기 - GetFactorialDivision(topFactorial, divisorFactorial) /// <summary> /// 팩토리얼 분할 구하기 /// </summary> /// <param name="topFactorial">상위 팩토리얼</param> /// <param name="divisorFactorial">제수 팩토리얼</param> /// <returns>팩토리얼 분할</returns> private long GetFactorialDivision(int topFactorial, int divisorFactorial) { long result = 1; for(int i = topFactorial; i > divisorFactorial; i--) { result *= i; } return result; } #endregion #region 순열 구하기 - GetPermutation(totalCount, extractionCount) /// <summary> /// 순열 구하기 /// </summary> /// <param name="totalCount">전체 수</param> /// <param name="extractionCount">추출 수</param> /// <returns>순열</returns> private long GetPermutation(int totalCount, int extractionCount) { return GetFactorialDivision(totalCount, totalCount - extractionCount); } #endregion #region 팩토리얼 구하기 - GetFactorial(int i) /// <summary> /// 팩토리얼 구하기 /// </summary> /// <param name="value">값</param> /// <returns>팩토리얼</returns> private long GetFactorial(int value) { if(value <= 1) { return 1; } return value * GetFactorial(value - 1); } #endregion |