Example of Java algorithm for solving full permutation problem based on recursion

2020-11-18 06:11:06
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An example of Java is presented in this paper to solve the permutation problem recursively. To share for your reference, the details are as follows:

Permutation problem

Set R = {r1, r2,... ,rn} is the n elements to be arranged, Ri=R-{ri}. The full arrangement of the elements in the set x is denoted as Perm(X). (ri)Perm(X) represents the arrangement obtained by prefixing ri to each permutation of the full arrangement Perm(X). The full arrangement of R can be summarized as follows:

When n=1, Perm(R)=(r), where r is the only element in the set;

When n > At 1 o 'clock, Perm(R) consisted of (r1)Perm(R1),(r2)Perm(R2),(r3)Perm(R3)... (rn) Perm (Rn).


public class AllSort {
  public static void perm(int[] list, int k, int m) {
    if( k == m) {
      for (int i = 0; i <=m; i++) {
        System.out.print(list[i]);
      }
      System.out.println();
    }
    else{
      for(int i = k; i <= m; i++) {
        swap(list,k,i);
        perm(list, k+1 , m);
        swap(list,k,i);
      }
    }
  }
  public static void swap(int[] list, int a, int b) {
    int temp;
    temp = list[a];
    list[a] = list[b];
    list[b] = temp;
  }
  public static void main(String args[]) {
    int[] list = new int[5];
    for(int i = 0; i < list.length; i++) {
      list[i] = i+1;
    }
    perm(list,0,list.length-1);
  }
}

Operation results:

For more information about java algorithm, please refer to Java Data Structure and Algorithm Tutorial, Java Operation of DOM Node Skills Summary, Java File and Directory Operation Skills Summary and Java Cache Operation Skills Summary.

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