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[N];
int visit[N];
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;
}

2013.1.10

trie实现。

其实题意就是统计出现最多次的的数字

用map做的ac代码：

#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;
}

用trie的ac代码：

#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;
}