UVA 10453 - Make Palindrome(DP）

#include <stdio.h>
#include <string.h>
int p[1001][1001];
int main()
{
char str[3001];
int i,j,len;
while(gets(str)!=0)
{
memset(p,0,sizeof(p));
len = strlen(str);
for(i = 1; i <= len; i ++)
{
for(j = 1; j <= len; j ++)
{
if(str[i-1] == str[len-j])
p[i][j] = p[i-1][j-1]+1;
else if(str[i-1] != str[len-j])
{
if(p[i-1][j] < p[i][j-1])
p[i][j] = p[i][j-1];
else
p[i][j] = p[i-1][j];
}
}
}
printf("%d ",len-p[len][len]);
for(i = len,j = len;;)
{
if(str[i-1] == str[len-j]&&i >= 1&&j >=1)
{
printf("%c",str[i-1]);
i --;j --;
}
else if(p[i][j] == p[i][j-1]&&j >= 1)
{
printf("%c",str[len-j]);
j --;
}
else if(p[i][j] == p[i-1][j]&&i >= 1)
{
printf("%c",str[i-1]);
i --;
}
else if(i == 0&&j == 0)
break;
}
printf("\n");
}
return 0;
}