第七周作业——最长递增子序列

#include "stdafx.h"
#include "string.h"
#include <iostream>
using namespace std;

enum decreaseDir {kInit = 0, kLeft, kUp, kLeftUp};

void LCS_Print(int **LCS_direction,
char* pStr1, char* pStr2,
size_t row, size_t col);

int LCS(char* pStr1, char* pStr2)
{
if(!pStr1 || !pStr2)
return 0;

size_t length1 = strlen(pStr1);
size_t length2 = strlen(pStr2);
if(!length1 || !length2)
return 0;

size_t i, j;

int **LCS_length;
LCS_length = (int**)(new int[length1]);
for(i = 0; i < length1; ++ i)
LCS_length[i] = (int*)new int[length2];

for(i = 0; i < length1; ++ i)
for(j = 0; j < length2; ++ j)
LCS_length[i][j] = 0;

int **LCS_direction;
LCS_direction = (int**)(new int[length1]);
for( i = 0; i < length1; ++ i)
LCS_direction[i] = (int*)new int[length2];

for(i = 0; i < length1; ++ i)
for(j = 0; j < length2; ++ j)
LCS_direction[i][j] = kInit;

for(i = 0; i < length1; ++ i)
{
for(j = 0; j < length2; ++ j)
{
//之前此处的代码有问题，现在订正如下：
if(i == 0 || j == 0)
{
if(pStr1[i] == pStr2[j])
{
LCS_length[i][j] = 1;
LCS_direction[i][j] = kLeftUp;
}
else
{
if(i > 0)
{
LCS_length[i][j] = LCS_length[i - 1][j];
LCS_direction[i][j] = kUp;
}
if(j > 0)
{
LCS_length[i][j] = LCS_length[i][j - 1];
LCS_direction[i][j] = kLeft;
}
}
}

else if(pStr1[i] == pStr2[j])
{
LCS_length[i][j] = LCS_length[i - 1][j - 1] + 1;
LCS_direction[i][j] = kLeftUp;
}

else if(LCS_length[i - 1][j] > LCS_length[i][j - 1])
{
LCS_length[i][j] = LCS_length[i - 1][j];
LCS_direction[i][j] = kUp;
}

else
{
LCS_length[i][j] = LCS_length[i][j - 1];
LCS_direction[i][j] = kLeft;
}
}
}
LCS_Print(LCS_direction, pStr1, pStr2, length1 - 1, length2 - 1); //调用下面的LCS_Pring 打印出所求子串。
return LCS_length[length1 - 1][length2 - 1];                      //返回长度。
}

void LCS_Print(int **LCS_direction,
char* pStr1, char* pStr2,
size_t row, size_t col)
{
if(pStr1 == NULL || pStr2 == NULL)
return;

size_t length1 = strlen(pStr1);
size_t length2 = strlen(pStr2);

if(length1 == 0 || length2 == 0 || !(row < length1 && col < length2))
return;

if(LCS_direction[row][col] == kLeftUp)
{
if(row > 0 && col > 0)
LCS_Print(LCS_direction, pStr1, pStr2, row - 1, col - 1);

printf("%c", pStr1[row]);
}
else if(LCS_direction[row][col] == kLeft)
{
if(col > 0)
LCS_Print(LCS_direction, pStr1, pStr2, row, col - 1);
}
else if(LCS_direction[row][col] == kUp)
{
if(row > 0)
LCS_Print(LCS_direction, pStr1, pStr2, row - 1, col);
}
}

int _tmain(int argc, _TCHAR* argv[])
{
char* pStr1="abcde";
char* pStr2="acde";
LCS(pStr1,pStr2);
printf("\n");
system("pause");
return 0;
}