CodeForces 712B Memory and Trident (水题，暴力)

题意：给定一个序列表示飞机要向哪个方向飞一个单位，让你改最少的方向，使得回到原点。

析：一个很简单的题，把最后的位置记录一下，然后要改的就是横坐标和纵坐标绝对值之和的一半。

代码如下：

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <cstdio>
#include <string>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <cstring>
#include <set>
#include <queue>
#include <algorithm>
#include <vector>
#include <map>
#include <cctype>
#include <cmath>
#include <stack>
#define freopenr freopen("in.txt", "r", stdin)
#define freopenw freopen("out.txt", "w", stdout)
using namespace std;

typedef long long LL;
typedef pair<int, int> P;
const int INF = 0x3f3f3f3f;
const double inf = 0x3f3f3f3f3f3f;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int maxn = 1e5 + 5;
const int mod = 1e9 + 7;
const int dr[] = {-1, 0, 1, 0};
const int dc[] = {0, 1, 0, -1};
const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};
int n, m;
const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
inline int Min(int a, int b){ return a < b ? a : b; }
inline int Max(int a, int b){ return a > b ? a : b; }
inline LL Min(LL a, LL b){ return a < b ? a : b; }
inline LL Max(LL a, LL b){ return a > b ? a : b; }
inline bool is_in(int r, int c){
    return r >= 0 && r < n && c >= 0 && c < m;
}
char s[maxn];

int main(){
    while(scanf("%s", s) == 1){
        n = strlen(s);
        int x = 0, y = 0;
        for(int i = 0; i < n; ++i){
            if(s[i] == 'R')  ++x;
            else if(s[i] == 'L')  --x;
            else if(s[i] == 'U')  ++y;
            else --y;
        }
        int ans = abs(x) + abs(y);
        if(ans & 1)  printf("-1\n");
        else printf("%d\n", ans/2);
    }
    return 0;
}