C++ 在序列上执行特定操作
假设我们给定一个空序列和 n 个查询,我们需要处理这些查询。这些查询以数组查询形式给出,并采用 {查询,数据} 的格式。查询可以是以下三种类型之一:
query = 1:将提供的数据添加到序列末尾。
query = 2:打印序列开头元素。之后删除元素。
query = 3:按升序对序列进行排序。
请注意,查询类型 2 和 3 始终具有数据 = 0。
因此,如果输入为 n = 9,查询 = {{1, 5}, {1, 4}, {1, 3}, {1, 2}, {1, 1}, {2, 0}, {3, 0}, {2, 0}, {3, 0}},则输出为 5 和 1。
每个查询后的序列如下所示:
- 1: {5}
- 2: {5, 4}
- 3: {5, 4, 3}
- 4: {5, 4, 3, 2}
- 5: {5, 4, 3, 2, 1}
- 6: {4, 3, 2, 1},打印 5。
- 7: {1, 2, 3, 4}
- 8: {2, 3, 4},打印 1。
- 9: {2, 3, 4}
为解决这个问题,我们将遵循以下步骤:
priority_queue<int> priq
Define one queue q
for initialize i := 0, when i < n, update (increase i by 1), do:
operation := first value of queries[i]
if operation is same as 1, then:
x := second value of queries[i]
insert x into q
otherwise when operation is same as 2, then:
if priq is empty, then:
print first element of q
delete first element from q
else:
print -(top element of priq)
delete top element from priq
otherwise when operation is same as 3, then:
while (not q is empty), do:
insert (-first element of q) into priq and sort
delete element from q示例
让我们看看以下实现,以获得更好的理解:
#include <bits/stdc++.h>
using namespace std;
void solve(int n, vector<pair<int, int>> queries){
priority_queue<int> priq;
queue<int> q;
for(int i = 0; i < n; i++) {
int operation = queries[i].first;
if(operation == 1) {
int x;
x = queries[i].second;
q.push(x);
} else if(operation == 2) {
if(priq.empty()) {
cout << q.front() << endl;
q.pop();
} else {
cout << -priq.top() << endl;
priq.pop();
}
} else if(operation == 3) {
while(!q.empty()) {
priq.push(-q.front());
q.pop();
}
}
}
}
int main() {
int n = 9; vector<pair<int, int>> queries = {{1, 5}, {1, 4}, {1, 3}, {1, 2}, {1, 1}, {2, 0}, {3, 0}, {2, 0}, {3, 0}};
solve(n, queries);
return 0;
}输入
9, {{1, 5}, {1, 4}, {1, 3}, {1, 2}, {1, 1}, {2, 0}, {3, 0}, {2, 0}, {3, 0}}
输出
5 1
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