HDU 1800 简单贪心 13.1.10用trie重做 ---其实是统计出现次数最多的单词

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 3010;
int a
;
int visit
;
int main()
{
int n;
while(cin >> n)
{
memset(a, 0, sizeof(a));
memset(visit, 0, sizeof(visit));
for(int i = 0; i < n; i++)
scanf("%d", &a[i]);

sort(a, a+n);

int cnt = 0; //扫走数
for(int i = 0; i < n; i++)
{
if(visit[i] == 1)
continue;
int pri = a[i];
cnt++;
for(int j  = i + 1; j < n && visit[i] == 0; j++)
{
if(a[j] > pri && visit[j] != 1)
{
visit[j] = 1;
pri = a[j];
}
}
}
cout << cnt << endl;
}
return 0;
}

#include <iostream>
#include <map>
using namespace std;

int main()
{
int n;
while(cin >> n) {
map<int, int> bm;
int temp;
for(int i = 0; i < n; i++) {
scanf("%d", &temp);
bm[temp]++;
}
int maxval = -1;
for(map<int, int>::iterator iter = bm.begin(); iter != bm.end(); ++iter)
{
if(iter->second > maxval)
maxval = iter->second;
}
cout << maxval << endl;
}

return 0;
}

#include <iostream>
#include <cstdio>
#include <string.h>
#include <string>
#include <malloc.h>
using namespace std;

int zero = 0;
struct Trie {
int count;
struct Trie* trie[10];
}*root;

void init() {
root = new Trie;
for(int i = 0; i < 10; i++)
root->trie[i] = NULL;
}

int insert(char s[]) {
Trie * head = root;
int len = strlen(s);
int j = -1;
for(int i = 0; i < len; i++) { //将数字前面的0除去
if(s[i] != '0') {
j = i;
break;
}
}
if(j == -1) {
zero++;
return zero;
}
for(int i = j; i < len; i++) {
int k = s[i] - '0';
if(head->trie[k] != NULL) {
head = head->trie[k];
} else {
head->trie[k] = new Trie;
head = head->trie[k];
head->count = 0;
for(int z = 0; z < 10;  z++)
head->trie[z] = NULL;
}
}
head->count++;
return head->count;
}

void del(Trie* p) {
for(int i = 0; i < 10; i++) {
if(p->trie[i] != NULL) {
del(p->trie[i]);
}
}
delete p;
}

int main() {
int count;
while(~scanf("%d", &count)) {
zero = 0;
init();
char ss[31];
int max = 0;
while(count--) {
scanf("%s", ss);
int num = insert(ss);
if(num > max)
max = num;
}
printf("%d\n", max);
del(root);
}
return 0;
}