Python 代码

算法1

前缀和

n = int(input())
N = n
chafen = {}
while(n):
    n-=1
    x1,x2 = map(int,input().split())
    if(chafen.get(x1)!=None):
        chafen[x1]+=1
    else:
        chafen[x1]=1
    if(chafen.get(x2+1)!=None):
        chafen[x2+1]-=1
    else:
        chafen[x2+1]=-1
qianzhuihe = 0 
ans = 0
chafen_list =[]
for key,value in chafen.items():
    chafen_list.append((key,value))
chafen_list.sort(key = lambda x:x[0])

for i in range(len(chafen_list)):
    qianzhuihe += chafen_list[i][1]

    ans = max(ans,qianzhuihe)

print(ans)

算法2

小根堆

import heapq
n = int(input())
nums = []
for _ in range(n):
    nums.append(tuple(map(int,input().split())))
nums.sort(key = lambda x:x[0])
heap = []
heapq.heapify(heap)
for i in range(0,n):
    if(i==0 or nums[i][0]<=heap[0]):
        heapq.heappush(heap,nums[i][1])
    else:
        heapq.heappushpop(heap,nums[i][1])
print(len(heap))