POJ_3356_LCS

//============================================================================
// Name        : POJ_3356_LCS.cpp
// Author      : tiger
// Version     :
// Copyright   : Your copyright notice
// Description : LCS的变形
// 如果匹配的话 dp[i][j] = min (dp[i-1][j-1], dp[i-1][j] + 1, dp[i][j-1] + 1);
// 否则：dp[i][j] = min (dp[i - 1][j], dp[i - 1][j - 1], dp[i][j - 1]) + 1;
// 初始化：dp[0][i] = i;            dp[i][0] = i;
//============================================================================

#include <iostream>
using namespace std;
int dp[2][1002];
int len1,len2;
char s1[1005],s2[1005];

int _LCS()
{
 int current=0;
 int i,j;
 int max= len1>len1?len1:len2;
 for(j = 0; j <= max;j++ )
 {
  dp[!current][j] = j;
  dp[current][j] = 0;

 }

 for(i = 1; i <= len1; i++)
 {
  for(j = 1; j <= len2; j++)
  {
   if(j==1)
   {
    dp[current][j-1] = i;
    dp[!current][j-1] = i-1;
   }
   if(dp[!current][j] < dp[current][j-1])
    dp[current][j] = dp[!current][j]+1;
   else
    dp[current][j] = dp[current][j-1] +1 ;
   if(s1[i] == s2[j] && dp[!current][j-1] < dp[current][j])
   {
    dp[current][j] = dp[!current][j-1];
   }
   else
   {

    if(dp[!current][j-1]+1 < dp[current][j] )
     dp[current][j] = dp[!current][j-1] + 1;

   }

    //printf("%d ",dp[current][j]);
  }
  //printf("/n");
  current = !current;
 }
 return dp[!current][j-1];
}
int main() {
 freopen("in","r",stdin);
 while(scanf("%d",&len1) != EOF )
 {
  if(len1)
   scanf("%s",s1+1);

  scanf("%d",&len2);
  if(len2)
  scanf("%s",s2+1);

  if(len1 == 0 || len2 == 0)
  {
    printf("%d/n",len2+len1);
  }else
  {
   printf("%d/n",_LCS());
  }
 }
 return 0;
}