Find the number of duplicates (or missing) in a continuous positive integer sequence.

There is a simple problem: given n-m + 2 (or N-m) composed of Positive IntegersDisordered SequenceThe elements are positive integers from m to n (n> m> = 1), and only one is repeated (or missing. How to find the number? (Assume that the missing number is not N or M)

ByIvonyThe difference or algorithm proposed.

1. Because the difference or algorithm in the closed range of [M, N] is not considered for the moment, [M-1] ^ [1, N] is used to indirectly obtain [m, n] the exclusive or of this closed interval.

2. Find the exclusive or of the array to be evaluated, and compare the result with the exclusive or result of [M, N] above, you can get the unique number of duplicates (or the missing number)

1 using system. LINQ; 2 using system; 3 namespace consoleapplication3 4 {5 class program 6 {7 static void main (string [] ARGs) 8 {9 int [] intergers = {11, 8, 9, 6, 12, 7, 5, 10, 810, 8}; // [5, 14], one more console. writeline (getrepeatorlack (intergers); 11 console. readkey (); 12} 13 // a disordered sequence consisting of n-m + 2 (or N-m) integers, whose elements are different integers from m to n, and only one is repeated (or missing. This algorithm returns the number of 14 Private Static int getrepeatorlack (INT [] arrints) 15 {16 int temp = 0; 17 int upper = arrints. length; 18 // temp is the variance of all numbers in the array arrints or result 19 for (INT I = 0; I <upper; I ++) 20 {21 temp = temp ^ arrints [I]; 22} 23 return temp ^ getxor (arrints. min (), arrints. max () + 1 ); 24} 25 /// <summary> 26 /// returns the XOR of several consecutive integers from start to end. Result 27 /// </Summary> 28 // <param name = "start"> Start position (inclusive) </param> 29 // <Param name = "end"> end position (not included) </param> 30 /// <returns> [start, end-1] closed interval variance or result </returns> 31 Private Static int getxor (INT start, int end) 32 {33 If (Start> = end) 34 {35 throw new argumentexception ("end must be greater than start"); 36} 37 If (start + 1 = END) 38 {39 return 0; 40} 41 return getxorfrom1ton (start) ^ getxorfrom1ton (end ); 42} 43 // <summary> 44 // returns the XOR or result of several consecutive integers from 1 to end. 45 /// </Summary> 46 // <param name = "end"> end position (not included) </param> 47 // <returns> [1, end-1] returns an exception or result of a closed interval </returns> 48 Private Static int getxorfrom1ton (INT end) 49 {50 if (end <= 1) 51 {52 throw new argumentexception ("the end parameter must be greater than or equal to 2"); 53} 54 if (2 = end) 55 {56 return 0; 57} 58 int mod = (end-1) % 4; 59 switch (MOD) 60 {61 case 0: 62 Return end-1; 63 Case 1: 64 return 1; 65 Case 2: 66 return end; 67 case 3: 68 return 0; 69 default: 70 return 0; 71} 72} 73 74 # region [1, N] The returns or differences of continuous positive integers in the closed range are regular 75 // we found [1, n] The variance or result of a continuous positive integer in the closed interval is regular, that is, 76 // remainder [1, n] exclusive or result xor77 // 0 n78 // 1 179 // n mod 4 = 2 N + 180 // 3 081 // so the following method can be transformed into the above 82 // Private Static int getxor (INT start, int end) 83 // {84 // int result = 0; 85 // If (start + 1 = END) 86 // {87 // return 0; 88 //} 89 // For (INT I = start; I <end; I ++) 90 // {91 // result = Result ^ I; 92 //} 93 // return result; 94 //} 95 # endregion96 97} 98}

 

Find the number of duplicates (or missing) in a continuous positive integer sequence.