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q0494.py
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q0494.py
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#!/usr/bin/python3
from typing import List
class Solution:
def findTargetSumWays(self, nums: List[int], target: int) -> int:
sum = 0
for num in nums:
sum += num
if target > sum or (sum - target) % 2 != 0:
return 0
border = (sum - target) >> 1
length = len(nums)
dp = [[0 for _ in range(border + 1)] for _ in range(length + 1)]
dp[0][0] = 1
for i in range(1, length + 1):
num = nums[i - 1]
for j in range(border + 1):
if j < num:
dp[i][j] = dp[i - 1][j]
else:
dp[i][j] = dp[i - 1][j - num] + dp[i - 1][j]
return dp[length][border]
def findTargetSumWays_map_solution(self, nums: List[int], target: int) -> int:
map = {}
if nums[0] == 0:
map = {0: 2}
else:
map = {nums[0]: 1, -nums[0]: 1}
for i in range(1, len(nums)):
new_map = {}
for key in map.keys():
new_key = key + nums[i]
if new_key in new_map:
new_map[new_key] += map[key]
else:
new_map[new_key] = map[key]
new_key = key - nums[i]
if new_key in new_map:
new_map[new_key] += map[key]
else:
new_map[new_key] = map[key]
map = new_map
if target in map:
return map[target]
else:
return 0
nums = [1,1,1,1,1]
target = 3
result = Solution().findTargetSumWays(nums, target)
print(result)