Codeforces 501B - Misha and Changing Handles (STL)

题意

有一些人改名字，输出每个人的原名和改了之后的名字.

思路

用map记录每个人换过的名字，用set记录是不是一个新的人，如果是的话就放到数组里。

代码

  
  
  
  

   
   
   
   
#include <cstdio>
   
   
   
   
#include <stack>
   
   
   
   
#include <list>
   
   
   
   
#include <set>
   
   
   
   
#include <iostream>
   
   
   
   
#include <string>
   
   
   
   
#include <vector>
   
   
   
   
#include <queue>
   
   
   
   
#include <functional>
   
   
   
   
#include <cstring>
   
   
   
   
#include <iomanip>
   
   
   
   
#include <algorithm>
   
   
   
   
#include <cctype>
   
   
   
   
#include <string>
   
   
   
   
#include <map>
   
   
   
   
#include <cmath>
   
   
   
   
using namespace std;
   
   
   
   
#define LL long long
   
   
   
   
#define ULL unsigned long long
   
   
   
   
#define SZ(x) (int)x.size()
   
   
   
   
#define Lowbit(x) ((x) & (-x))
   
   
   
   
#define MP(a, b) make_pair(a, b)
   
   
   
   
#define MS(arr, num) memset(arr, num, sizeof(arr))
   
   
   
   
#define PB push_back
   
   
   
   
#define F first
   
   
   
   
#define S second
   
   
   
   
#define ROP freopen("input.txt", "r", stdin);
   
   
   
   
#define MID(a, b) (a + ((b - a) >> 1))
   
   
   
   
#define LC rt << 1, l, mid
   
   
   
   
#define RC rt << 1|1, mid + 1, r
   
   
   
   
#define LRT rt << 1
   
   
   
   
#define RRT rt << 1|1
   
   
   
   
#define BitCount(x) __builtin_popcount(x)
   
   
   
   
#define BitCountll(x) __builtin_popcountll(x)
   
   
   
   
#define LeftPos(x) 32 - __builtin_clz(x) - 1
   
   
   
   
#define LeftPosll(x) 64 - __builtin_clzll(x) - 1
   
   
   
   
const double PI = acos(-1.0);
   
   
   
   
const int INF = 0x3f3f3f3f;
   
   
   
   
const double eps = 1e-8;
   
   
   
   
const int MAXN = 1000 + 10;
   
   
   
   
const int MOD = 1000007;
   
   
   
   
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
   
   
   
   
typedef pair<int, int> pii;
   
   
   
   
typedef vector<int>::iterator viti;
   
   
   
   
typedef vector<pii>::iterator vitii;
   
   
   
   

   
   
   
   
vector<string> ans;
   
   
   
   
set<string> st;
   
   
   
   
map<string, string> mp;
   
   
   
   

   
   
   
   
int main()
   
   
   
   
{
   
   
   
   
 // ROP;
   
   
   
   
 int n, i, j;
   
   
   
   
 cin >> n;
   
   
   
   
 for (i = 0; i < n; i++)
   
   
   
   
 {
   
   
   
   
 string from, to;
   
   
   
   
 cin >> from >> to;
   
   
   
   
 st.insert(to);
   
   
   
   
 if (!st.count(from)) ans.PB(from);
   
   
   
   
 mp[from] = to;
   
   
   
   
 }
   
   
   
   
 cout << SZ(ans) << endl;
   
   
   
   
 for (i = 0; i < SZ(ans); i++)
   
   
   
   
 {
   
   
   
   
 string tmp = ans[i];
   
   
   
   
 while (mp.count(mp[tmp])) tmp = mp[tmp];
   
   
   
   
 cout << ans[i] << " " << mp[tmp] << endl;
   
   
   
   
 }
   
   
   
   
 return 0;
   
   
   
   
}