Codeforces 821C-Okabe and Boxes
2017-06-26 23:04
507 查看
Okabe and Boxes
time limit per test
3 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Okabe and Super Hacker Daru are stacking and removing boxes. There are n boxes numbered from 1 to n.
Initially there are no boxes on the stack.
Okabe, being a control freak, gives Daru 2n commands: n of
which are to add a box to the top of the stack, and n of which are to remove a box from the top of the stack and throw it in the trash.
Okabe wants Daru to throw away the boxes in the order from 1 to n.
Of course, this means that it might be impossible for Daru to perform some of Okabe's remove commands, because the required box is not on the top of the stack.
That's why Daru can decide to wait until Okabe looks away and then reorder the boxes in the stack in any way he wants. He can do it at any point of time between Okabe's commands, but he can't add or remove boxes while he does it.
Tell Daru the minimum number of times he needs to reorder the boxes so that he can successfully complete all of Okabe's commands. It is guaranteed that every box is added before it is required to be removed.
Input
The first line of input contains the integer n (1 ≤ n ≤ 3·105) —
the number of boxes.
Each of the next 2n lines of input starts with a string "add"
or "remove". If the line starts with the "add", an integer x (1 ≤ x ≤ n)
follows, indicating that Daru should add the box with number x to the top of the stack.
It is guaranteed that exactly n lines contain "add"
operations, all the boxes added are distinct, and n lines contain "remove"
operations. It is also guaranteed that a box is always added before it is required to be removed.
Output
Print the minimum number of times Daru needs to reorder the boxes to successfully complete all of Okabe's commands.
Examples
input
output
input
output
Note
In the first sample, Daru should reorder the boxes after adding box 3 to the stack.
In the second sample, Daru should reorder the boxes after adding box 4 and box 7 to
the stack.
题意:模拟一个栈,有两种操作,栈顶增加一个元素,栈顶移除一个元素,要求元素按照编号大小移除,移除前可以选择是否调整栈内元素顺序,询问最少调整次数
解题思路:用vector模拟过程,遇到不满足时,将vector清空
#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <queue>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <climits>
using namespace std;
#define LL long long
const int INF = 0x3f3f3f3f;
int n, x;
char ch[30];
int main()
{
while (~scanf("%d", &n))
{
vector<int>g;
int ans = 0, cnt=1;
for (int i = 1; i <= 2 * n; i++)
{
scanf("%s", ch);
if (!strcmp(ch, "add"))
{
scanf("%d", &x);
g.push_back(x);
}
else
{
if (g.empty());
else if (g.back() == cnt) g.pop_back();
else
{
ans++;
g.clear();
}
cnt++;
}
}
printf("%d\n", ans);
}
return 0;
}
time limit per test
3 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Okabe and Super Hacker Daru are stacking and removing boxes. There are n boxes numbered from 1 to n.
Initially there are no boxes on the stack.
Okabe, being a control freak, gives Daru 2n commands: n of
which are to add a box to the top of the stack, and n of which are to remove a box from the top of the stack and throw it in the trash.
Okabe wants Daru to throw away the boxes in the order from 1 to n.
Of course, this means that it might be impossible for Daru to perform some of Okabe's remove commands, because the required box is not on the top of the stack.
That's why Daru can decide to wait until Okabe looks away and then reorder the boxes in the stack in any way he wants. He can do it at any point of time between Okabe's commands, but he can't add or remove boxes while he does it.
Tell Daru the minimum number of times he needs to reorder the boxes so that he can successfully complete all of Okabe's commands. It is guaranteed that every box is added before it is required to be removed.
Input
The first line of input contains the integer n (1 ≤ n ≤ 3·105) —
the number of boxes.
Each of the next 2n lines of input starts with a string "add"
or "remove". If the line starts with the "add", an integer x (1 ≤ x ≤ n)
follows, indicating that Daru should add the box with number x to the top of the stack.
It is guaranteed that exactly n lines contain "add"
operations, all the boxes added are distinct, and n lines contain "remove"
operations. It is also guaranteed that a box is always added before it is required to be removed.
Output
Print the minimum number of times Daru needs to reorder the boxes to successfully complete all of Okabe's commands.
Examples
input
3 add 1 remove add 2 add 3 remove remove
output
1
input
7
add 3
add 2add 1remove
add 4
remove
remove
remove
add 6
add 7
add 5
remove
remove
remove
output
2
Note
In the first sample, Daru should reorder the boxes after adding box 3 to the stack.
In the second sample, Daru should reorder the boxes after adding box 4 and box 7 to
the stack.
题意:模拟一个栈,有两种操作,栈顶增加一个元素,栈顶移除一个元素,要求元素按照编号大小移除,移除前可以选择是否调整栈内元素顺序,询问最少调整次数
解题思路:用vector模拟过程,遇到不满足时,将vector清空
#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <queue>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <climits>
using namespace std;
#define LL long long
const int INF = 0x3f3f3f3f;
int n, x;
char ch[30];
int main()
{
while (~scanf("%d", &n))
{
vector<int>g;
int ans = 0, cnt=1;
for (int i = 1; i <= 2 * n; i++)
{
scanf("%s", ch);
if (!strcmp(ch, "add"))
{
scanf("%d", &x);
g.push_back(x);
}
else
{
if (g.empty());
else if (g.back() == cnt) g.pop_back();
else
{
ans++;
g.clear();
}
cnt++;
}
}
printf("%d\n", ans);
}
return 0;
}
相关文章推荐
- 栈 Okabe and Boxes:CodeForces - 821C
- Codeforces Round #420 (Div. 2) 821C - Okabe and Boxes 【思维题】
- codeforces 420 div2 C Okabe and Boxes
- codeforces 420-C. Okabe and Boxes
- 821C - Okabe and Boxes ——优先队列+手动模拟栈
- Okabe and Boxes CodeForces - 821C
- Codeforces 821 C. Okabe and Boxes
- codeforces -420-B. Okabe and Banana Trees
- coderforces round#420-C Okabe and Boxes
- 【codeforces 768F】 Barrels and boxes
- CodeForces - 260C Balls and Boxes(模拟)
- Codeforces Round #420 (Div. 2) C - Okabe and Boxes
- Codeforces Round #420 C. Okabe and Boxes
- Codeforces 821A-Okabe and Future Gadget Laboratory
- codeforce C. Okabe and Boxes
- codeforces 390C Inna and Candy Boxes
- CF Okabe and Boxes
- Codeforces 821B-Okabe and Banana Trees
- Codeforces#420 Okabe and Boxes
- [CF821C] Okabe and Boxes(模拟,栈)