leetcode@ [97] Interleaving Strings

https://leetcode.com/problems/interleaving-string/

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

For example,
Given:
s1 =

"aabcc"

,
s2 =

"dbbca"

,

When s3 =

"aadbbcbcac"

, return true.
When s3 =

"aadbbbaccc"

, return false.

class Solution {
public:
bool isInterleave(string s1, string s2, string s3) {
if(s1.length() + s2.length() != s3.length()) return false;
if(s1.length() == 0 && s2.length() == 0 && s3.length() == 0) return true;

vector<vector<bool> > dp(s1.length()+1, vector<bool>(s2.length()+1, false));
for(int i=1;i<=s1.length();++i) {
dp[i][0] = (s1.substr(0,i) == s3.substr(0,i))? true: false;
}
for(int j=1;j<=s2.length();++j) {
dp[0][j] = (s2.substr(0,j) == s3.substr(0,j))? true: false;
}

for(int i=1;i<=s1.length();++i) {
for(int j=1;j<=s2.length();++j) {
if(dp[i-1][j] && s1[i-1] == s3[i+j-1]) dp[i][j] = true;
else if(dp[i][j-1] && s2[j-1] == s3[i+j-1]) dp[i][j] = true;
else dp[i][j] = false;
}
}

return dp[s1.length()][s2.length()];
}
};

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