bool isInterleave(string s1, string s2, string s3) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if( s1.size() + s2.size() != s3.size() )
return false;
// save space
if( s2.size() > s1.size() ){
string temp = s1;
s1=s2;
s2=temp;
}
vector<bool> isInter(s2.size()+1, false);
// initialize the first row
for( int i = 0; i <= s2.size(); i++){
if( s2.substr(0,i) != s3.substr(0,i) )
break;
isInter[i] = true;
}
// treat each inner loop's isInter as isInter[i][j], the isInter[i-1][j] is the same as the one
// on the right side of the assign line inner most
for( int i = 1; i <= s1.size(); i ++){
isInter[0] = ( s1.substr(0,i) == s3.substr(0,i) );
for( int j = 1; j <= s2.size(); j++){
isInter[j]=(s2[j-1]==s3[i+j-1] && isInter[j-1] ) || ( s1[i-1]==s3[i+j-1] && isInter[j] );
}
}
return isInter[s2.size()];
}
bool isInter(string &s1, string &s2, string &s3, int pos1, int pos2)
{
int len1 = s1.size();
int len2 = s2.size();
int len3 = s3.size();
int pos3 = pos1+pos2;
if(pos3 == len3)
return true;
if(pos1< len1 && s1[pos1] ==s3[pos3])
{
if(isInter(s1, s2, s3, pos1+1, pos2))
return true;
}
if(pos2< len2 && s2[pos2] ==s3[pos3])
{
if(isInter(s1, s2, s3, pos1, pos2+1))
return true;
}
return false;
}
bool isInterleave(string s1, string s2, string s3) {
if( s1.size() + s2.size() != s3.size() ) return false;
vector<vector<bool>> isInter( s1.size()+1, vector<bool>(s2.size()+1, false) );
isInter[0][0] = true;
int it = 1;
while( it <= s1.size() && s1[it-1] == s3[it-1] ){
isInter[it][0] = true;
it ++;
}
it = 1;
while( it <= s2.size() && s2[it-1] == s3[it-1] ){
isInter[0][it] = true;
it ++;
}
for( int s1_it = 1; s1_it <= s1.size(); s1_it ++ ){
for( int s2_it = 1; s2_it <= s2.size(); s2_it ++ ){
// check if isInter[s1_it][s2_it] is true?
// two cases
char temp_char = s3[s1_it + s2_it -1] ;
// if s1[s1_it-1] == s3[s1_it + s2_it -1], isInter[s1_it][s2_it] will be true
// if isInter[s1_it - 1][s2_it] is true
if( temp_char == s1[s1_it-1] )
isInter[s1_it][s2_it] = isInter[s1_it-1][s2_it];
if( temp_char == s2[s2_it-1] )
isInter[s1_it][s2_it] = isInter[s1_it][s2_it-1] || isInter[s1_it][s2_it];
}
}
return isInter[s1.size()][s2.size()];
}
bool isInterleave(string s1, string s2, string s3) {
if(s1.size()+s2.size() != s3.size())
return false;
return isInter(s1, s2, s3, 0, 0);
}