poj 3617 Best Cow Line 【贪心】

Best Cow Line

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 14715 Accepted: 4187

Description

FJ is about to take his N (1 ≤ N ≤ 2,000) cows to the annual"Farmer of the Year" competition. In this contest every farmer arranges his cows in a line and herds them past the judges.

The contest organizers adopted a new registration scheme this year: simply register the initial letter of every cow in the order they will appear (i.e., If FJ takes Bessie, Sylvia, and Dora in that order he just registers BSD). After the registration phase ends, every group is judged in increasing lexicographic order according to the string of the initials of the cows' names.

FJ is very busy this year and has to hurry back to his farm, so he wants to be judged as early as possible. He decides to rearrange his cows, who have already lined up, before registering them.

FJ marks a location for a new line of the competing cows. He then proceeds to marshal the cows from the old line to the new one by repeatedly sending either the first or last cow in the (remainder of the) original line to the end of the new line. When he's finished, FJ takes his cows for registration in this new order.

Given the initial order of his cows, determine the least lexicographic string of initials he can make this way.

Input

* Line 1: A single integer: N
* Lines 2..N+1: Line i+1 contains a single initial ('A'..'Z') of the cow in the ith position in the original line

Output

The least lexicographic string he can make. Every line (except perhaps the last one) contains the initials of 80 cows ('A'..'Z') in the new line.

Sample Input

6ACDBCB

Sample Output

ABCBCD

Source

USACO 2007 November Silver

思路:

             刚开始的时候输入一定序列的字符串，然后通过取第一个或者最后一个来放到一个新的字符串的末尾来创建一个字典序最小的字符串！

          通过一个循环，来判断到底是输出左边的字符还是输出右边的字符，然后每次输出之后，都要将对应的下标进行相应的变化！

         注意：输出格式！每行最多80个字符！

代码：

#include <stdio.h>#include <string.h>#include <algorithm>using namespace std;char a[2005];int main(){int n;while(scanf("%d",&n)!=EOF){getchar();for(int i=0;i<n;i++){scanf("%c",&a[i]);getchar();}int u=0,v=n-1,t=0;while(u<=v){int left=0;for(int i=0;u+i<=v;i++){if(a[u+i]<a[v-i]){left=1;break;}else if(a[u+i]>a[v-i]){left=0;break;}}if(t==80){t=0;printf("\n");}if(left){printf("%c",a[u++]);t++;}else{printf("%c",a[v--]);t++;}}printf("\n");}return 0;}