Record: C # programming magic number 6174

A four-digit magic number.

Description:

Step 1: split each digit into four digits;

Step 2: Use the four digits split in step 1 to form a maximum of four digits and a minimum of four digits;

Step 3: subtract the minimum number from the maximum number in step 2. If the difference is 6174, the fourth digit in the first step is a magic number. Otherwise, the first step is performed for the difference, after 15 cycles.

Code:

/** Created by SharpDevelop. * User: Ajax * Date: Saturday * Time: ** the following code is used to determine whether a four-digit number meets the mathematical 6174-digit number */using System; namespace Demo2 {class Program {public static void Main (string [] args) {// number detected: {5643,5140} // number detected: {1111,9999} int startNumber = 5643; int initNumber = startNumber; int [] number = new int [4]; int maxNumber = 0; int minNumber = 0; // count is used to count the number of cycles. To ensure that no endless loop occurs, int coun T = 15; int tempCount = count; // because count times may not detect 6174 numbers, // so it indicates that if the print output of the count jump out of the loop "is used for count Detection, it still cannot be judged as a 6174 number" bool flag = true; do {tempCount --; if (tempCount <0) {flag = false; break;} // each time the loop body is entered, the two values return to the initial value maxNumber = 0; minNumber = 0; int index = 0; int initNumberTemp = initNumber; while (initNumberTemp> 0) {int temp = initNumberTemp % 10; initNumberTemp/= 10; number [index] = temp; Console. write (n Umber [index] + ""); index ++;} Console. writeLine (); Console. writeLine ("Step 1: Split numbers =" + initNumber + "= complete"); // sort the numbers in the array from large to small (less efficient Bubble Sorting) for (int I = 0; I <number. length-1; I ++) {for (int j = I + 1; j <number. length; j ++) {if (number [I] <number [j]) {int temp = number [I]; number [I] = number [j]; number [j] = temp ;}}// print the number sequence Console after sorting from large to small. write ("Step 2: print the order of numbers sorted in ascending order"); for (int j = 0; j <number. lengt H; j ++) {Console. write (number [j] + "");} Console. writeLine (); // The maxcompute Console after merging and sorting. write ("Step 3: The largest numeric value after sorting"); for (int I = 0; I <number. length; I ++) {maxNumber = maxNumber * 10 + number [I];} Console. writeLine (maxNumber); // sorts the numbers in the array from small to large (essentially exchange, dependent on the sorting in the second step above) for (int I = 0; I <number. length/2; I ++) {int temp = number [I]; number [I] = number [number. length-1-I]; number [number. length-1-I] = t Emp;} // print the number sequence Console after the output is sorted in ascending order. write ("Step 4: print the order of numbers in ascending order"); for (int j = 0; j <number. length; j ++) {Console. write (number [j] + "");} Console. writeLine (); // The minimum number Console after merging and sorting. write ("Step 5: minimum number after sorting"); for (int I = 0; I <number. length; I ++) {minNumber = minNumber * 10 + number [I];} Console. writeLine (minNumber);} while (initNumber = maxNumber-minNumber )! = 6174); // The result is judged and the final output if (flag) {Console. writeLine ("{0} is a 6174 number", startNumber);} else {Console. writeLine ("{0} detection still cannot judge {1} is a 6174 number", count, startNumber);} Console. readKey ();}}}

Running result diagram:

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In fact, if each digit in four digits is the same, it cannot constitute a magic character number. Because the difference between the maximum number and the minimum number is always equal to 0.

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