8VC Venture Cup 2016 - Elimination Round A. Robot Sequence 暴力

A. Robot Sequence

题目连接：

http://www.codeforces.com/contest/626/problem/A

Description

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.

Sample Input

6

URLLDR

Sample Output

2

Hint

题意

给你一个命令，然后让你输出这个命令中有多少个子串的起点和终点是一样的

题解：

数据范围只有200，所以直接n^2暴力就好了

记录一下前缀和。

其实不记录前缀和 n^3也是兹瓷的

代码

#include<bits/stdc++.h>
using namespace std;

const int maxn = 503;
char s[maxn];
int x[maxn],y[maxn];

int main()
{
    int n;
    scanf("%d",&n);
    scanf("%s",s+1);
    for(int i=1;i<=n;i++)
    {
        x[i]=x[i-1];
        y[i]=y[i-1];
        if(s[i]=='U')x[i]++;
        if(s[i]=='D')x[i]--;
        if(s[i]=='L')y[i]++;
        if(s[i]=='R')y[i]--;
    }
    int ans = 0;
    for(int i=0;i<=n;i++)
        for(int j=i+1;j<=n;j++)
            if(x[i]-x[j]==0&&y[i]-y[j]==0)
                ans++;
    cout<<ans<<endl;
}