http://acm.hdu.edu.cn/showproblem.php?pid=1075

C++版本一

题解：字典树||map

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=500000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q;
int ans,cnt,flag,temp;
int a[N][26];
char str[N],rec[N],str1[N],str2[N];
map<string,string>p;
bool en[N];
char cp[N][20];
void insert(char *s,char *s2){
    int len=strlen(s),p=0;
    for(int i=0;i<len;i++){
        int ch=s[i]-'a';
        if(a[p][ch]==0)a[p][ch]=++cnt;
        p=a[p][ch];
    }
    en[p]=1;
    strcpy(cp[p],s2);
}
void search(char* s){
    int len=strlen(s),p=0;
    for(int i=0;i<len;i++){
        int ch=s[i]-'a';
        if(a[p][ch]==0){
            printf("%s",s);
            return;
        }
        p=a[p][ch];
    }
    if(en[p])
        printf("%s",cp[p]);
    else
        printf("%s",s);

}

int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //scanf("%d",&n);
    //scanf("%d",&t);
    //while(t--){}
    scanf("%s",str);
    while(scanf("%s",str)){
        if(strcmp(str,"END")==0)
            break;
        scanf("%s",str2);
        insert(str2,str);
    }
    scanf("%s",str);
    getchar();
        while (gets(str) && strcmp(str, "END")) {
            int len = strlen(str);
            int idx = 0;
            for (int i=0;i<=len - 1;i++) {
                if (islower(str[i])) {
                    rec[idx++] = str[i];
                } else {
                    rec[idx] = 0;
                    search(rec);
                    idx = 0;
                    printf("%c", str[i]);
                }
            }
            puts("");
        }

    //cout << "Hello world!" << endl;
    return 0;
}

C++版本二

题解：

可以用map赤裸裸地做，但是比较花费时间，虽然这题时间给了5s，map解法是能过的。 
不过Trie解法500+ms，果然Trie字典树才是正解啊。 
Trie入门题。

另外发现ios_base::sync_with_stdio(0)这句话是关闭IO同步的，如果把cin和gets混用就不同步...坑了好久..

#include <cstdio>
#include <cstring>
#include <cctype>
#include <map>
#include <iostream>
#include <algorithm>
using namespace std;
 
#define repf(i,a,b) for(int i=(a);i<=(b);i++)
typedef long long ll;
 
string a, b;
char s[3010];
map<string, string> mp;
 
int main() {
	// ios_base::sync_with_stdio(0);
	cin >> a;
	while (cin >> a) {
		if (a == "END")
			break;
		cin >> b;
		mp[b] = a;
	}
	cin >> a;
	getchar();
	while (1) {
		gets(s);
		if (!strcmp(s, "END"))
			break;
		int len = strlen(s);
		a = "";
		repf (i, 0, len - 1) {
			if (islower(s[i])) {
				a += s[i];
			} else {
				if (mp.find(a) != mp.end())
					cout << mp[a];
				else
					cout << a;
				a = "";
				cout << s[i];
			}
		}
		cout << endl;
	}
	return 0;
}

C++版本三

#include <cstdio>
#include <cstring>
#include <cctype>
#include <iostream>
#include <algorithm>
using namespace std;
 
#define repf(i,a,b) for(int i=(a);i<=(b);i++)
typedef long long ll;
 
const int N = 3010;
const int SIZE = 26;
 
// pointer trie
struct Node {
	char* val;
	Node *next[SIZE];
};
 
struct PTrie {
	Node *root;
	PTrie() { root = newNode(); }
	void init() { del(root); root = newNode(); }
	inline int idx(char c) { return c - 'a'; }
 
	Node *newNode() {
		Node *u = new Node;
		repf (i, 0, SIZE - 1) {
			u->next[i] = NULL;
		}
		u->val = NULL;
		return u;
	}
 
	void insert(char *s, char *v) {
		Node *u = root;
		int len = strlen(s);
		repf (i, 0, len - 1) {
			int c = idx(s[i]);
			if (u->next[c] == NULL)
				u->next[c] = newNode();
			u = u->next[c];
		}
		u->val = new char[11];
		strcpy(u->val, v);
	}
 
	void find(char *s) {
		Node*u = root;
		int len = strlen(s);
		repf (i, 0, len - 1) {
			int c = idx(s[i]);
			if (u->next[c] == NULL) {
				printf("%s", s);
				return;
			}
			u = u->next[c];
		}
		if (u->val)
			printf("%s", u->val);
		else
			printf("%s", s);
	}
 
	void del(Node *rt) {
		if (rt == NULL)
			return;
		else {
			repf (i, 0, SIZE - 1)
				if (rt->next[i])
					del(rt->next[i]);
		}
		delete rt->val;
		delete rt;
	}
} trie;
 
char a[11], b[11];
char str[N], rec[N];
 
int main() {
	// ios_base::sync_with_stdio(0);
	scanf("%s", a);
	while (scanf("%s %s\n", a, b) && strcmp(a, "END")) {
		//cout << a << b << endl;
		trie.insert(b, a);
	}
	while (gets(str) && strcmp(str, "END")) {
		int len = strlen(str);
		int idx = 0;
		repf (i, 0, len - 1) {
			if (islower(str[i])) {
				rec[idx++] = str[i];
			} else {
				rec[idx] = 0;
				trie.find(rec);
				idx = 0;
				printf("%c", str[i]);
			}
		}
		puts("");
	}
}