CodeForces 748C Santa Claus and Robot (思维)

题意：给定一个机器人的行走路线，求最少的点能使得机器人可以走这样的路线。

析：每次行走，记录一个方向向量，每次只有是相反方向时，才会增加一个点，最后再加上最后一个点即可。

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>
#include <sstream>
#define debug() puts("++++");
#define gcd(a, b) __gcd(a, b)
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define freopenr freopen("in.txt", "r", stdin)
#define freopenw freopen("out.txt", "w", stdout)
using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<double, int> P;
const int INF = 0x3f3f3f3f;
const double inf = 0x3f3f3f3f3f3f;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int maxn = 1e4 + 10;
const int mod = 1e6;
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 bool is_in(int r, int c){
  return r >= 0 && r < n && c >= 0 && c < m;
}

int main(){
  map<char, int> mp;
  mp['L'] = 0;  mp['U'] = 1;  mp['D'] = 2; mp['R'] = 3;
  string s;
  cin >> n >> s;
  if(1 == n){ cout << "1\n";  return 0; }
  int ans = 0;
  int dx = 0, dy = 0, pos = 0;
  for(int i = 0; i < s.size(); ++i){
    if(s[i] == 'U'){
      if(dy >= 0) dy = 1;
      else ++ans, dy = 1, dx = 0;
    }
    else if(s[i] == 'D'){
      if(dy <= 0)  dy = -1;
      else ++ans, dy = -1, dx = 0;
    }
    else if(s[i] == 'L'){
      if(dx <= 0)  dx = -1;
      else ++ans, dx = -1, dy = 0;
    }
    else{
      if(dx >= 0)  dx = 1;
      else ++ans, dx = 1, dy = 0;
    }
  }
  ++ans;
  printf("%d\n", ans);
  return 0;
}