forked from haoel/leetcode
-
Notifications
You must be signed in to change notification settings - Fork 0
/
NumberOfStudentsUnableToEatLunch.cpp
75 lines (73 loc) · 2.96 KB
/
NumberOfStudentsUnableToEatLunch.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
// Source : https://leetcode.com/problems/number-of-students-unable-to-eat-lunch/
// Author : Hao Chen
// Date : 2021-05-10
/*****************************************************************************************************
*
* The school cafeteria offers circular and square sandwiches at lunch break, referred to by numbers 0
* and 1 respectively. All students stand in a queue. Each student either prefers square or circular
* sandwiches.
*
* The number of sandwiches in the cafeteria is equal to the number of students. The sandwiches are
* placed in a stack. At each step:
*
* If the student at the front of the queue prefers the sandwich on the top of the stack, they
* will take it and leave the queue.
* Otherwise, they will leave it and go to the queue's end.
*
* This continues until none of the queue students want to take the top sandwich and are thus unable
* to eat.
*
* You are given two integer arrays students and sandwiches where sandwiches[i] is the type of the
* ith sandwich in the stack (i = 0 is the top of the stack) and students[j] is the preference of
* the jth student in the initial queue (j = 0 is the front of the queue). Return the number of
* students that are unable to eat.
*
* Example 1:
*
* Input: students = [1,1,0,0], sandwiches = [0,1,0,1]
* Output: 0
* Explanation:
* - Front student leaves the top sandwich and returns to the end of the line making students =
* [1,0,0,1].
* - Front student leaves the top sandwich and returns to the end of the line making students =
* [0,0,1,1].
* - Front student takes the top sandwich and leaves the line making students = [0,1,1] and sandwiches
* = [1,0,1].
* - Front student leaves the top sandwich and returns to the end of the line making students =
* [1,1,0].
* - Front student takes the top sandwich and leaves the line making students = [1,0] and sandwiches =
* [0,1].
* - Front student leaves the top sandwich and returns to the end of the line making students = [0,1].
* - Front student takes the top sandwich and leaves the line making students = [1] and sandwiches =
* [1].
* - Front student takes the top sandwich and leaves the line making students = [] and sandwiches = [].
* Hence all students are able to eat.
*
* Example 2:
*
* Input: students = [1,1,1,0,0,1], sandwiches = [1,0,0,0,1,1]
* Output: 3
*
* Constraints:
*
* 1 <= students.length, sandwiches.length <= 100
* students.length == sandwiches.length
* sandwiches[i] is 0 or 1.
* students[i] is 0 or 1.
******************************************************************************************************/
class Solution {
public:
int countStudents(vector<int>& students, vector<int>& sandwiches) {
int st[2] = {0};
for(auto s: students) {
st[s]++;
}
int cnt = 0;
for(auto& san : sandwiches){
if (st[san] == 0) break;
st[san]--;
cnt++;
}
return students.size() - cnt;
}
};