8VC Venture Cup 2016 - Elimination Round-A. Robot Sequence（模拟）

最新推荐文章于 2020-11-25 20:04:34 发布

梧桐下的四叶草

最新推荐文章于 2020-11-25 20:04:34 发布

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分类专栏： codeforces 文章标签： codeforces 模拟

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Calvin the robot lies in an infinite rectangular grid. Calvin's source code contains a list of n commands, each either 'U', 'R', 'D', or 'L' — instructions to move a single square up, right, down, or left, respectively. How many ways can Calvin execute a non-empty contiguous substrings of commands and return to the same square he starts in? Two substrings are considered different if they have different starting or ending indices.

Input

The first line of the input contains a single positive integer, n (1 ≤ n ≤ 200) — the number of commands.

The next line contains n characters, each either 'U', 'R', 'D', or 'L' — Calvin's source code.

Output

Print a single integer — the number of contiguous substrings that Calvin can execute and return to his starting square.

        Examples 
      
          input 
        
6
URLLDR

          output 
        
2

          input 
        
4
DLUU

          output 
        
0

          input 
        
7
RLRLRLR

          output 
        
12

Note

In the first case, the entire source code works, as well as the "RL" substring in the second and third characters.

Note that, in the third case, the substring "LR" appears three times, and is therefore counted three times to the total result.

题意：

给出上下左右给你，问你在字符串【L，R】范围里有几个子串能回到开始时的位置。

思路：

题目给出的数据范围较小，果断暴力，暴力L，与R就行了，两重for循环枚举L，R就行了。

AC代码：

#include<iostream>
#include<functional>
#include<algorithm>
#include<cstring>
#include<string>
#include<vector>
#include<cstdio>
#include<cmath>
#include<map>
using namespace std;
#define CRL(a) memset(a,0,sizeof(a))
typedef unsigned __int64 LL;
typedef  __int64 ll;
#define CMP bool cmp(const node& a,const node& b){	return a.R<b.R||(a.R==b.R&&a.L<b.L); }
const int T = 503000;
const int mod = 1000000007;

struct node
{
	int U,D,L,R;
	friend void operator+(node& a,node& b){
		a.D += b.D,a.L += b.L;
		a.R += b.R,a.U += b.U;
	}
}a[500];

void fun(char s,node& b)
{
	if(s=='U')b.U++;
	else if(s=='D')b.D++;
	else if(s=='L')b.L++;
	else b.R++;
}

bool jugde(node a,node b)
{
	b.D -= a.D,b.L -= a.L;
	b.R -= a.R,b.U -= a.U;
	if(b.U==b.D&&b.L==b.R)
		return true;
	return false;
}

int main()
{
#ifdef zsc
    freopen("input.txt","r",stdin);
#endif

	int n,m,i,j,k;
	char s[500];

	while(~scanf("%d",&n))
	{
		memset(a,0,sizeof a);
		scanf("%s",&s);
		fun(s[0],a[1]);
		for(i=1;i<n;++i){
			fun(s[i],a[i+1]);
			a[i+1] + a[i];
		}
		k = 0;
		for(i=0;i<n;++i){
			for(j=i+1;j<=n;++j){
				if(jugde(a[i],a[j])){
					k++;
				}
			}
		}
		printf("%d\n",k);
	}

    return 0;
}