leetcode

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.

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算法

DP O（n^2）

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class Solution { public: bool isInterleave(string s1, string s2, string s3) { if (s3.length() != s1.length() + s2.length()) return false; int len1 = s1.length(), len2 = s2.length(); vector<vector<bool> > dp(len1 + 1, vector<bool>(len2 + 1, true)); // init for (int i = 1; i <= len1; ++i) dp[i][0] = dp[i - 1][0] && (s1[i - 1] == s3[i - 1]); for (int j = 1; j <= len2; ++j) dp[0][j] = dp[0][j - 1] && (s2[j - 1] == s3[j - 1]); // dp for (int i = 1; i <= len1; ++i) for (int j = 1; j <= len2; ++j) dp[i][j] = (dp[i - 1][j] && s3[i + j - 1] == s1[i - 1]) || (dp[i][j - 1] && s3[i + j - 1] == s2[j - 1]); return dp[len1][len2]; } };