1 class Solution { 2 public: 3 bool isInterleave(string s1, string s2, string s3) { 4 if(s3.size() != s1.size() + s2.size()) 5 return false; 6 //create indicator 7 vector<vector<bool> > match(s1.size() + 1, vector<bool>(s2.size() + 1, false)); 8 //initialization the first row and the first column 9 match[0][0] = true; 10 for( int l1 = 1; l1 <= s1.size(); ++ l1 ) { 11 char c1 = s1[l1 - 1]; 12 char c3 = s3[l1 - 1]; 13 if (c1 == c3) { 14 match[l1][0] = true; 15 } else 16 break; 17 } 18 for( int l2 = 1; l2 <= s2.size(); ++ l2 ) { 19 char c2 = s2[l2 - 1]; 20 char c3 = s3[l2 - 1]; 21 if (c2 == c3) { 22 match[0][l2] = true; 23 } else 24 break; 25 } 26 //work through the rest of matrix using the formula 27 for( int l1 = 1; l1 <= s1.size(); ++ l1 ) { 28 char c1 = s1[l1 - 1]; 29 for( int l2 = 1 ; l2 <= s2.size() ; ++ l2 ) { 30 char c2 = s2[l2 - 1]; 31 int l3 = l1 + l2; 32 char c3 = s3[l3 - 1]; 33 if (c1 == c3) { 34 match[l1][l2] = match[l1 - 1][l2] || match[l1][l2]; 35 } 36 if (c2 == c3) { 37 match[l1][l2] = match[l1][l2 - 1] || match[l1][l2]; 38 } 39 } 40 } 41 //the last element is the result 42 return match[s1.size()][s2.size()]; 43 } 44 };
