如何在java中查找數組的子數組

Question

這是一個程序，用於打印給定數組的所有可能的子數組，但邏輯中存在一些問題，並且它打印的是錯誤的輸出。

是否有任何算法來實現？

public class SubArray { 
static int[][] subArrs; 
static int count = 0; 

public static void main(String[] args) { 
    int[] arr = { 1, 2, 3 }; 
    int N = 8; 

    subArrs = new int[N][]; 
    subArrs[0] = new int[10]; 

    for (int i = 0; i < arr.length; i++) { 
     subArrs[i] = new int[1]; 
     subArrs[i][0] = arr[i]; 
    } 

    count = arr.length; 
    for (int i = 0; i < arr.length; i++) { 
     sub(arr, i, i); 
    } 

    for (int i = 0; i < subArrs.length; i++) { 
     System.out.print("[ "); 
     for (int j = 0; j < subArrs[i].length; j++) { 
      System.out.print(" " + subArrs[i][j]); 
     } 
     System.out.println(" ]"); 
    } 
} 

這是一種計算超過1個元素的子數組的方法。

static void sub(int arr[], int i, int index) { 
    for (int j = i + 1; j < arr.length; j++) { 

     while (index <= j) { 
      subArrs[count] = new int[j + 1]; 
      subArrs[count][0] = arr[i]; 

      for (int k = 1; k < (j + 1); k++) { 
       subArrs[count][k] = arr[k]; 
      } 
      count++; 
      index++; 
     } 
    } 

} 
} 

輸出我正在

[ 1 ] 
[ 2 ] 
[ 3 ] 
[ 1 2 ] 
[ 1 2 ] 
[ 1 2 3 ] 
[ 2 2 3 ] 
[ 2 2 3 ] 

所需的輸出

[ 1 ] 
[ 2 ] 
[ 3 ] 
[ 1 2 ] 
[ 1 3 ] 
[ 2 3 ] 
[ 1 2 3 ] 

Answer 1

嘗試此代碼：

for (int i = 0; i < yourArray.length; i++) 
    { 
     // j is the number of elements which should be printed 
     for (int j = i; j < yourArray.length; j++) 
     { 
      // print the array from i to j 
      for (int k = i; k <= j; k++) 
      { 
       System.out.print(yourArray[k]); 
      } 
      System.out.println(); 
     } 
    } 

Answer 2

公共類AD { 靜態最終字符串[] ABC = {「A B C D」};

public static void main(String[] args) { 
    System.out.println(JSON.toJSON(sub(Arrays.asList(abc), 1, abc.length))); 
} 

public static List<Object[]> sub(List list, int minSize, int maxSize) { 
    if (minSize <= 0) { 
     minSize = 1; 
    } 

    if (minSize > maxSize) { 
     maxSize = minSize; 
    } 

    if (maxSize > list.size()) { 
     maxSize = list.size(); 
    } 
    List<Object[]> ret = new ArrayList<>(); 
    for (int i = minSize; i <= maxSize; i++) { 
     ret.addAll(combine(abc, i)); 
    } 

    return ret; 
} 

public static List combine(Object[] a, int m) { 
    int n = a.length; 
    if (m > n) { 
     return null; 
    } 

    List result = new ArrayList(); 

    int[] bs = new int[n]; 
    for (int i = 0; i < n; i++) { 
     bs[i] = 0; 
    } 
    // 初始化 
    for (int i = 0; i < m; i++) { 
     bs[i] = 1; 
    } 
    boolean flag = true; 
    boolean tempFlag = false; 
    int pos = 0; 
    int sum = 0; 
    // 首先找到第一個10組合，然後變成01，同時將左邊所有的1移動到數組的最左邊 
    do { 
     sum = 0; 
     pos = 0; 
     tempFlag = true; 
     result.add(print(bs, a, m)); 

     for (int i = 0; i < n - 1; i++) { 
      if (bs[i] == 1 && bs[i + 1] == 0) { 
       bs[i] = 0; 
       bs[i + 1] = 1; 
       pos = i; 
       break; 
      } 
     } 
     // 將左邊的1全部移動到數組的最左邊 

     for (int i = 0; i < pos; i++) { 
      if (bs[i] == 1) { 
       sum++; 
      } 
     } 
     for (int i = 0; i < pos; i++) { 
      if (i < sum) { 
       bs[i] = 1; 
      } else { 
       bs[i] = 0; 
      } 
     } 

     // 檢查是否所有的1都移動到了最右邊 
     for (int i = n - m; i < n; i++) { 
      if (bs[i] == 0) { 
       tempFlag = false; 
       break; 
      } 
     } 
     if (tempFlag == false) { 
      flag = true; 
     } else { 
      flag = false; 
     } 

    } while (flag); 
    result.add(print(bs, a, m)); 

    return result; 
} 

private static Object[] print(int[] bs, Object[] a, int m) { 
    Object[] result = new Object[m]; 
    int pos = 0; 
    for (int i = 0; i < bs.length; i++) { 
     if (bs[i] == 1) { 
      result[pos] = a[i]; 
      pos++; 
     } 
    } 
    return result; 
} 

}

Answer 3

試試這個代碼： -

/* Java code to generate all possible subsequences. 
    Time Complexity O(n * 2^n) */ 

import java.math.BigInteger; 

class Test 
{ 
    static int arr[] = new int[]{1, 2, 3, 4}; 

    static void printSubsequences(int n) 
    { 
     /* Number of subsequences is (2**n -1)*/ 
     int opsize = (int)Math.pow(2, n); 

     /* Run from counter 000..1 to 111..1*/ 
     for (int counter = 1; counter < opsize; counter++) 
     { 
      for (int j = 0; j < n; j++) 
      { 
       /* Check if jth bit in the counter is set 
        If set then print jth element from arr[] */ 

       if (BigInteger.valueOf(counter).testBit(j)) 
        System.out.print(arr[j]+" "); 
      } 
      System.out.println(); 
     } 
    } 

    // Driver method to test the above function 
    public static void main(String[] args) 
    { 
     System.out.println("All Non-empty Subsequences"); 
     printSubsequences(arr.length); 
    } 
}