Package g0401_0500.s0494_target_sum

Class Solution

java.lang.Object

g0401_0500.s0494_target_sum.Solution

public class Solution
extends Object

494 - Target Sum.

Medium

You are given an integer array nums and an integer target.

You want to build an expression out of nums by adding one of the symbols '+' and '-' before each integer in nums and then concatenate all the integers.

• For example, if nums = [2, 1], you can add a '+' before 2 and a '-' before 1 and concatenate them to build the expression "+2-1".

Return the number of different expressions that you can build, which evaluates to target.

Example 1:

Input: nums = [1,1,1,1,1], target = 3

Output: 5

Explanation:

 There are 5 ways to assign symbols to make the sum of nums be target 3.
 -1 + 1 + 1 + 1 + 1 = 3
 +1 - 1 + 1 + 1 + 1 = 3
 +1 + 1 - 1 + 1 + 1 = 3
 +1 + 1 + 1 - 1 + 1 = 3
 +1 + 1 + 1 + 1 - 1 = 3 

Example 2:

Input: nums = [1], target = 1

Output: 1

Constraints:

• 1 <= nums.length <= 20
• 0 <= nums[i] <= 1000
• 0 <= sum(nums[i]) <= 1000
• -1000 <= target <= 1000

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	findTargetSumWays(int[] nums, int s)

Methods inherited from class java.lang.Object

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

Constructor Detail

Solution

public Solution()

Method Detail

findTargetSumWays

public int findTargetSumWays(int[] nums,
                             int s)