POJ 之 Hardwood Species

                                                     Hardwood Species

Time Limit:10000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

 

Description

Hardwoods are the botanical group of trees that have broad leaves, produce a fruit or nut, and generally go dormant in the winter.
America's temperate climates produce forests with hundreds of
hardwood species -- trees that share certain biological characteristics.
Although oak, maple and cherry all are types of hardwood trees, for
example, they are different species. Together, all the hardwood species
represent 40 percent of the trees in the United States.

On the other hand, softwoods, or conifers, from the Latin word
meaning "cone-bearing," have needles. Widely available US softwoods
include cedar, fir, hemlock, pine, redwood, spruce and cypress. In a
home, the softwoods are used primarily as structural lumber such as 2x4s
and 2x6s, with some limited decorative applications.

Using satellite imaging technology, the Department of Natural
Resources has compiled an inventory of every tree standing on a
particular day. You are to compute the total fraction of the tree
population represented by each species.

Input

Input
to your program consists of a list of the species of every tree
observed by the satellite; one tree per line. No species name exceeds 30
characters. There are no more than 10,000 species and no more than
1,000,000 trees.

Output

Print
the name of each species represented in the population, in alphabetical
order, followed by the percentage of the population it represents, to 4
decimal places.

Sample Input

Red Alder
Ash
Aspen
Basswood
Ash
Beech
Yellow Birch
Ash
Cherry
Cottonwood
Ash
Cypress
Red Elm
Gum
Hackberry
White Oak
Hickory
Pecan
Hard Maple
White Oak
Soft Maple
Red Oak
Red Oak
White Oak
Poplan
Sassafras
Sycamore
Black Walnut
Willow

Sample Output

Ash 13.7931
Aspen 3.4483
Basswood 3.4483
Beech 3.4483
Black Walnut 3.4483
Cherry 3.4483
Cottonwood 3.4483
Cypress 3.4483
Gum 3.4483
Hackberry 3.4483
Hard Maple 3.4483
Hickory 3.4483
Pecan 3.4483
Poplan 3.4483
Red Alder 3.4483
Red Elm 3.4483
Red Oak 6.8966
Sassafras 3.4483
Soft Maple 3.4483
Sycamore 3.4483
White Oak 10.3448
Willow 3.4483
Yellow Birch 3.4483

Hint

This problem has huge input, use scanf instead of cin to avoid time limit exceeded.

代码分析：（以后再写）

#include <stdio.h>
#include <string.h>
#include <string>
#include <cstring>
#include <map>
#include <algorithm>

using namespace std;

int main()
{
    char s[35];
    double  cnt;
    map<string, double>ma;
    map<string, double>::iterator it = ma.begin();

    cnt=0;
    while(gets(s)!=NULL)
    {
        ma[s]++;
        cnt++;
    }
    //int n=ma.size();

    //sort(ma.begin(), ma.end() );

    double dd;
    for(it=ma.begin(); it!=ma.end(); it++ )
    {
        dd = it->second*100.0/cnt;
        it->second = dd;
        printf("%s %.4lf\n", it->first.c_str(), dd );
    }

    return 0;
}