Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Program to find number of ways we can arrange symbols to get target in Python?
Suppose we have a list of non-negative numbers called nums and also have an integer target. We have to find the the number of ways to arrange + and - in nums such that the expression equals to target.
So, if the input is like nums = [2, 3, 3, 3, 2] target = 9, then the output will be 2, as we can have -2 + 3 + 3 + 3 + 2 and 2 + 3 + 3 + 3 – 2.
To solve this, we will follow these steps:
s := sum of all numbers in nums
if (s + target) mod 2 is not same as 0 or target > s, then
return 0
W := quotient of (s + target) / 2
dp1 := a list of size (W + 1) and fill with 0
dp1[0] := 1
dp2 := A list of size (W + 1) and fill with 0
for i in range 0 to size of nums, do
for j in range 0 to W + 1, do
if j >= nums[i], then
dp2[j] := dp2[j] + dp1[j - nums[i]]
for j in range 0 to W + 1, do
dp1[j] := dp1[j] + dp2[j]
dp2[j] := 0
return last element of dp1
Let us see the following implementation to get better understanding:
Example
class Solution: def solve(self, nums, target): s = sum(nums) if (s + target) % 2 != 0 or target > s: return 0 W = (s + target) // 2 dp1 = [0] * (W + 1) dp1[0] = 1 dp2 = [0] * (W + 1) for i in range(len(nums)): for j in range(W + 1): if j >= nums[i]: dp2[j] += dp1[j - nums[i]] for j in range(W + 1): dp1[j] += dp2[j] dp2[j] = 0 return dp1[-1] ob = Solution() nums = [2, 3, 3, 3, 2] target = 9 print(ob.solve(nums, target))
Input
[2, 3, 3, 3, 2], 9
Output
2
85 Views
