POJ 2250 Compromise

本文介绍了一种解决最长公共子序列问题的算法,并通过一个具体示例详细展示了如何使用该算法来找出两段文本之间的最长公共单词序列。此算法采用动态规划方法,通过构建二维数组来记录两个输入序列中每个位置上的最长公共子序列长度。
Compromise
Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 5486 Accepted: 2478 Special Judge

Description

In a few months the European Currency Union will become a reality. However, to join the club, the Maastricht criteria must be fulfilled, and this is not a trivial task for the countries (maybe except for Luxembourg). To enforce that Germany will fulfill the criteria, our government has so many wonderful options (raise taxes, sell stocks, revalue the gold reserves,...) that it is really hard to choose what to do. 

Therefore the German government requires a program for the following task: 
Two politicians each enter their proposal of what to do. The computer then outputs the longest common subsequence of words that occurs in both proposals. As you can see, this is a totally fair compromise (after all, a common sequence of words is something what both people have in mind). 

Your country needs this program, so your job is to write it for us.

Input

The input will contain several test cases. 
Each test case consists of two texts. Each text is given as a sequence of lower-case words, separated by whitespace, but with no punctuation. Words will be less than 30 characters long. Both texts will contain less than 100 words and will be terminated by a line containing a single '#'. 
Input is terminated by end of file.

Output

For each test case, print the longest common subsequence of words occuring in the two texts. If there is more than one such sequence, any one is acceptable. Separate the words by one blank. After the last word, output a newline character.

Sample Input

die einkommen der landwirte
sind fuer die abgeordneten ein buch mit sieben siegeln
um dem abzuhelfen
muessen dringend alle subventionsgesetze verbessert werden
#
die steuern auf vermoegen und einkommen
sollten nach meinung der abgeordneten
nachdruecklich erhoben werden
dazu muessen die kontrollbefugnisse der finanzbehoerden
dringend verbessert werden
#

Sample Output

die einkommen der abgeordneten muessen dringend verbessert werden
题目大意:给定两段文本,每段以‘#’结束,打印出两段文本中的最长公共单词。
解题方法:类似于最长公共子序列。
#include <stdio.h>
#include <string.h>
#include <iostream>
using namespace std;

char text1[105][35];
char text2[105][35];
int index[105][105];
int dp[105][105];

void Print(int i, int j)
{
    if (i >= 1 && j >= 1)
    {
        if (index[i][j] == 0)
        {
            Print(i - 1, j - 1);
            if (dp[i][j] != 1)
            {
                printf(" ");
            }
            printf("%s", text1[i - 1]);
        }
        else
        {
            if (index[i][j] == 1)
            {
                Print(i - 1, j);
            }
            else
            {
                if (index[i][j] == 2)
                {
                    Print(i, j - 1);
                }
            }
        }
    }
}

int main()
{
    int nLen1 = -1, nLen2 = -1;
    while(cin>>text1[++nLen1])
    {
        while(cin>>text1[++nLen1])
        {
            if (text1[nLen1][0] == '#')
            {
                break;
            }
        }
        while(cin>>text2[++nLen2])
        {
            if (text2[nLen2][0] == '#')
            {
                break;
            }
        }
        for (int i = 0; i <= nLen1; i++)
        {
            dp[i][0] = 0;
        }
        for (int i = 0; i <= nLen2; i++)
        {
            dp[0][i] = 0;
        }
        for (int i = 1; i <= nLen1; i++)
        {
            for (int j = 1; j <= nLen2; j++)
            {
                if (strcmp(text1[i - 1], text2[j - 1]) == 0)
                {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                    index[i][j] = 0;
                }
                else
                {
                    if (dp[i - 1][j] > dp[i][j - 1])
                    {
                        dp[i][j] = dp[i - 1][j];
                        index[i][j] = 1;
                    }
                    else
                    {
                        dp[i][j] = dp[i][j - 1];
                        index[i][j] = 2;
                    }
                }
            }
        }
        Print(nLen1, nLen2);
        printf("\n");
        nLen1 = nLen2 = -1;
    }
    return 0;
}

 

转载于:https://www.cnblogs.com/lzmfywz/p/3164021.html

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