Java Implementation Bubble Sort

Bubble Sort:

Is two elements that are contiguous by index, assuming greater than/less than (depending on whether an ascending or descending row is required). Then replace, or not change.

Such a round down. Compare n-1 times. n equals the number of elements; n-2, n-3 ... Until the last round. 1 more times.

So the comparison is decremented: from n-1 to 1

Then the total number of times is: 1+2+3+...+ (n-1), calculated in a linear formula: (1+n-1)/2* (n-1) ==> n/2* (n-1) ==> (n^2-n) * 0.5

Use large o to indicate the time complexity of the algorithm: O (n^2), ignoring the coefficients 0.5 and constant-n

public class Bubblesort {public static void main (string[] args) {int len = 10;int[] ary = new Int[len]; Random random = new random (), for (int j = 0; J < Len; J + +) {Ary[j] = random.nextint (1000);} SYSTEM.OUT.PRINTLN (------before-------Sort); for (int j = 0; J < Ary.length; J + +) {System.out.print (Ary[j] + "");} /* * Ascending. ASC1 and ASC2 optimize the comparison times for internal loops. Better than the total number of times: * Asc1, ASC2: (1+n-1)/2* (n-1) ==> n/2* (n-1) ==> N (n-1)/2 ==> (N^2-N)/2 * asc:n^2-n *///orderasc (ary );//orderasc2 (ary); orderAsc1 (ary);//descending, just need to infer the size of the replacement}static void Orderasc (int[] ary) {int count = 0;//the number of times int len = ary . length;for (int j = 0; J < Len; J + +) {//outer fixed loop count for (int k = 0; k < len-1; k++) {//inner fixed loop count if (Ary[k] > Ary[k + 1]) {Ary[k] = ary[k + 1] + (ary[k + 1] = ary[k]) * 0;//One-step interchange/* Swap two variable values * a=a+b * b=a-b * a=a-b * *} count++;} System.out.println ("\ n-----orderasc in ascending order------number of times:" + count); for (int j = 0; J < Len; J + +) {System.out.print (Ary[j] + " ");}} static void OrderAsc1 (int[] ary) {int count = 0;//number of times intLen = ary.length;for (int j = 0; J < Len; J + +) {//outer fixed loop count for (int k = len-1; k > J; k--) {//inner layer from multiple to less decrement ratio if (ary[k ] < Ary[k-1]) {ary[k] = Ary[k-1] + (ary[k-1] = ary[k]) * 0;//one-step Exchange} count++;}  System.out.println ("\ n-----orderAsc1 in ascending order------number of times:" + count); for (int j = 0; J < Len; J + +) {System.out.print (Ary[j] + " ");}} static void OrderAsc2 (int[] ary) {int count = 0;//the number of times int len = ary.length;for (int j = len-1; j > 0; j--) {//outer fixed loop secondary Number */* k < J;  Total comparison times = (n^2-n)/2 */for (int k = 0; k < J; k++) {//The inner layer is decremented from many to less if (Ary[k] > ary[k + 1]) {Ary[k] = ary[k + 1] + (ary[k + 1] = ary[k]) * 0;//One-step Exchange}count++;}}  System.out.println ("\ n-----orderAsc2 in ascending order------number of times:" + count); for (int j = 0; J < Len; J + +) {System.out.print (Ary[j] + " ");}}}

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Java Implementation Bubble Sort