Given several boxes with different colors represented by different positive numbers.
You may experience several rounds to remove boxes until there is no box left. Each time you can choose some continuous boxes with the same color (composed of k boxes, k >= 1), remove them and get k*k points.
Find the maximum points you can get.
Example 1:
Input:
[1, 3, 2, 2, 2, 3, 4, 3, 1]
Output:
23
Explanation:
[1, 3, 2, 2, 2, 3, 4, 3, 1]
----> [1, 3, 3, 4, 3, 1] (3*3=9 points)
----> [1, 3, 3, 3, 1] (1*1=1 points)
----> [1, 1] (3*3=9 points)
----> [] (2*2=4 points)
My code:
class Solution(object):
def removeBoxes(self, boxes):
"""
:type boxes: List[int]
:rtype: int
"""
N = len(boxes)
self.boxes = boxes
self.dp = [[[-1]* N for i in range(N)] for j in range(N)]
return self.search(0, N-1, 0)
def search(self, l, r, k):
if l > r:
return 0
if self.dp[l][r][k] != -1:
return self.dp[l][r][k]
while l < r and self.boxes[r] == self.boxes[r-1]:
r -= 1
k += 1
self.dp[l][r][k] = self.search(l, r-1, 0) + (k + 1) * (k + 1)
for i in range(l, r):#Here r is the updated r
if self.boxes[i] == self.boxes[r]:
#print('l %d r %d executed result %d'%(i,r,self.search(l,i,k+1)))
self.dp[l][r][k] = max(self.dp[l][r][k], self.search(l,i,k+1)+self.search(i+1,r-1,0))#Here is the consideration that we finally get the combination of boxes[i]
return self.dp[l][r][k]