Alignment of Code，ACM/ICPC NEERC 2010,UVa 1593

You are working in a team that writes Incredibly Customizable Programming Codewriter (ICPC) which is basically a text editor with bells and whistles. You are working on a module that takes a piece of code containing some definitions or other tabular information and aligns each column on a fixed vertical position, while keeping the resulting code as short as possible, making sure that only whitespaces that are absolutely required stay in the code. So, that the first words on each line are printed at position p1 = 1; the second words on each line are printed at the minimal possible position p2, such that all first
words end at or before position p2 − 2; the third words on each line are printed at the minimal possible position p3, such that all second words end at or before position p3 − 2, etc. For the purpose of this problem, the code consists of multiple lines. Each line consists of one or more words separated by spaces. Each word can contain uppercase and lowercase Latin letters, all ASCII punctuation marks, separators, and other non-whitespace ASCII characters (ASCII codes 33 to 126 inclusive). Whitespace consists of space characters (ASCII code 32).
Input
The input file contains one or more lines of the code up to the end of file. All lines (including the last
one) are terminated by a standard end-of-line sequence in the file. Each line contains at least one word,
each word is 1 to 80 characters long (inclusive). Words are separated by one or more spaces. Lines of
the code can have both leading and trailing spaces. Each line in the input file is at most 180 characters
long. There are at most 1000 lines in the input file.
Output
Write to the output file the reformatted, aligned code that consists of the same number of lines, with
the same words in the same order, without trailing and leading spaces, separated by one or more spaces
such that i-th word on each line starts at the same position pi.
Note for the Sample:
The ‘⊔’ character in the example below denotes a space character in the actual files (ASCII code32).
Sample Input
␣␣start:␣␣integer;␣␣␣␣//␣begins␣here
stop:␣integer;␣//␣␣ends␣here
␣s:␣␣string;
c:␣␣␣char;␣//␣temp

Sample Output
start:␣integer;␣//␣begins␣here
stop:␣␣integer;␣//␣ends␣␣␣here
s:␣␣␣␣␣string;
c:␣␣␣␣␣char;␣␣␣␣//␣temp

题目大意：输入若干行代码，要求每列的单词的左边界对齐并且尽量靠左。单词之间至少要空一格。

题解：相信大家都可以想到就是记录输入中，每一列的最长的单词长度，之后输出时，每列以最长的那个单词为基准输出，不足就输出空格。可是该如何做到输入时记录每一列是最长的单词长度呢？这里需要介绍一下一个神奇的东西：stringstream。

stringsteam在本题的用处就是，将一行的输入，按空格拆分成一个一个单词。想了解stringsteam的具体用处，大家可自行百度。

AC代码：

#include<iostream>#include<string>#include<sstream>#include<vector>#include<cstdio>using namespace std;const int MAXN=1005;vector<string> File[MAXN];int maxlen[200];int main(){//  freopen("in.txt","r",stdin);    string line;    int row=0;    while(getline(cin,line)){        stringstream ss(line);//创建一个字符串流        int col=0;        string buf;        while(ss>>buf){//将一行字符串，拆成一个单词形式的字符串            File[row].push_back(buf);            if(!row||maxlen[col]<buf.length())//记录每一列最长的单词长度                maxlen[col]=buf.length();            col++;        }        row++;    }    for(int r=0;r<row;r++){        for(int c=0;c<File[r].size();c++){            int l=maxlen[c]-File[r][c].length();            cout<<File[r][c];            if(c<File[r].size()-1)            for(int i=0;i<=l;i++){//输出空格                cout<<" ";             }        }        cout<<endl;    }    return 0;}