记录了初步解题思路 以及本地实现代码；并不一定为最优 也希望大家能一起探讨 一起进步
目录
5/15 1072. 按列翻转得到最大值等行数
def maxEqualRowsAfterFlips(matrix):
"""
:type matrix: List[List[int]]
:rtype: int
"""
from collections import defaultdict
n,m=len(matrix),len(matrix[0])
mem=defaultdict(int)
for i in range(n):
tag = ""
for j in range(m):
tag+=str((0^matrix[i][0])^matrix[i][j])
mem[tag]+=1
return max(mem.values())
5/16 1335. 工作计划的最低难度
def minDifficulty(jobDifficulty, d):
"""
:type jobDifficulty: List[int]
:type d: int
:rtype: int
"""
n = len(jobDifficulty)
if d>n:
return -1
mem = {}
def dfs(d,ind):
if (d,ind) in mem:
return mem[(d,ind)]
if d==0:
return max(jobDifficulty[:ind+1])
ans = float("inf")
mx = 0
for k in range(ind,d-1,-1):
mx = max(mx,jobDifficulty[k])
ans = min(ans,dfs(d-1,k-1)+mx)
mem[(d,ind)] = ans
return ans
return dfs(d-1,n-1)
5/17 2446. 判断两个事件是否存在冲突
def haveConflict(event1, event2):
"""
:type event1: List[str]
:type event2: List[str]
:rtype: bool
"""
def trans(s):
l = s.split(":")
return 60*int(l[0])+int(l[1])
s1,e1 = trans(event1[0]),trans(event1[1])
s2,e2 = trans(event2[0]),trans(event2[1])
if e1<s2 or e2<s1:
return False
return True
5/18 1073. 负二进制数相加
def addNegabinary(arr1, arr2):
"""
:type arr1: List[int]
:type arr2: List[int]
:rtype: List[int]
"""
i,j=len(arr1)-1,len(arr2)-1
ans = []
c = 0
while i>=0 or j>=0 or c:
x = c
if i>=0:
x+=arr1[i]
if j>=0:
x+=arr2[j]
if x>=2:
ans.append(x-2)
c = -1
elif x>=0:
ans.append(x)
c = 0
else:
ans.append(1)
c = 1
i-=1
j-=1
while len(ans)>1 and ans[-1]==0:
ans.pop()
return ans[::-1]
5/19 1079. 活字印刷
def numTilePossibilities(tiles):
"""
:type tiles: str
:rtype: int
"""
from collections import Counter
def dfs(cnt):
ans = 0
for i,x in cnt.items():
if x>0:
ans +=1
cnt[i]-=1
ans += dfs(cnt)
cnt[i]+=1
return ans
cnt = Counter(tiles)
return dfs(cnt)
5/20 1373. 二叉搜索子树的最大键值和
class TreeNode(object):
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
def maxSumBST(root):
"""
:type root: TreeNode
:rtype: int
"""
global ans
ans = 0
def dfs(node):
global ans
if node is None:
return True,float("-inf"),float("inf"),0
lbst,lmax,lmin,lsum = dfs(node.left)
rbst,rmax,rmin,rsum = dfs(node.right)
if lbst and rbst and lmax<node.val and rmin>node.val:
s = lsum+rsum+node.val
ans = max(ans,s)
return True,max(rmax,node.val),min(lmin,node.val),s
return False,0,0,0
dfs(root)
return ans
5/21 LCP 33. 蓄水
def storeWater(bucket, vat):
"""
:type bucket: List[int]
:type vat: List[int]
:rtype: int
"""
n = len(bucket)
maxk = max(vat)
if maxk==0:
return 0
ans = float("inf")
for k in range(1,maxk+1):
up = 0
for i in range(n):
up += max(0,(vat[i]+k-1)//k-bucket[i])
ans=min(ans,up+k)
return ans
