java - Find next greater number with same set of digits

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import java.util.Arrays; import java.util.stream.IntStream; import array._Array; public class _Math2 { /** * Find next greater number with same set of digits * * http://www.geeksforgeeks.org/find-next-greater-number-set-digits/ * */ static int next_greater_number_with_same_set_of_digits(long num) { System.out.println(num); int zeroChar = (int)'0'; int array[] = String.valueOf(num).chars().map(i -> i - zeroChar).toArray(); int[] temp = Arrays.copyOf(array, array.length); Arrays.sort(temp); //check if array in increasing order if(Arrays.equals(array, temp)) { _Array.swap(array, array.length - 2, array.length - 1); return combineNumber(array); } _Array.reverse(temp); //check if num is max possible number is this set of digits if(Arrays.equals(array, temp)) throw new Error("Not Possible"); temp = Arrays.copyOf(array, array.length); //sort except first number Arrays.sort(temp, 1, array.length); //find first digit which does not match with original numbers digit in same index int start = 1; while(array[start] == temp[start]) start++; //swap it _Array.swap(temp, start - 1, start); return combineNumber(temp); } public static int combineNumber(int[] array) { int sum = 0; for (int j = 0; j < array.length; j++) sum += array[j]*Math.pow(10, array.length - j - 1); return sum; } }

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