Package g0201_0300.s0282_expression_add_operators

Class Solution

java.lang.Object
g0201_0300.s0282_expression_add_operators.Solution
public class Solution extends java.lang.Object
282 - Expression Add Operators.

Hard

Given a string num that contains only digits and an integer target, return all possibilities to insert the binary operators '+', '-', and/or '*' between the digits of num so that the resultant expression evaluates to the target value.

Note that operands in the returned expressions should not contain leading zeros.

Example 1:

Input: num = “123”, target = 6

Output: [“1*2*3”,“1+2+3”]

Explanation: Both “1*2*3” and “1+2+3” evaluate to 6.

Example 2:

Input: num = “232”, target = 8

Output: [“2*3+2”,“2+3*2”]

Explanation: Both “2*3+2” and “2+3*2” evaluate to 8.

Example 3:

Input: num = “105”, target = 5

Output: [“1*0+5”,“10-5”]

Explanation:

 Both "1*0+5" and "10-5" evaluate to 5.
 Note that "1-05" is not a valid expression because the 5 has a leading zero.

Example 4:

Input: num = “00”, target = 0

Output: [“0*0”,“0+0”,“0-0”]

Explanation:

 "0*0", "0+0", and "0-0" all evaluate to 0.
 Note that "00" is not a valid expression because the 0 has a leading zero.

Example 5:

Input: num = “3456237490”, target = 9191

Output: []

Explanation: There are no expressions that can be created from “3456237490” to evaluate to 9191.

Constraints:

  • 1 <= num.length <= 10
  • num consists of only digits.
  • -231 <= target <= 231 - 1

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    java.util.List<java.lang.String>
    addOperators(java.lang.String num, int target)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • addOperators

      public java.util.List<java.lang.String> addOperators(java.lang.String num, int target)