Today I have done leetcode's June LeetCoding Challenge with cpp.

June LeetCoding Challenge 14

Description

Delete Operation for Two Strings

Given two strings word1 and word2, return the minimum number of steps required to make word1 and word2 the same.

In one step, you can delete exactly one character in either string.

Example 1:

Input: word1 = "sea", word2 = "eat"
Output: 2
Explanation: You need one step to make "sea" to "ea" and another step to make "eat" to "ea".

Example 2:

Input: word1 = "leetcode", word2 = "etco"
Output: 4

Constraints:

• 1 <= word1.length, word2.length <= 500
• word1 and word2 consist of only lowercase English letters.

Solution

class Solution {
  int LCS(string &s1, string &s2) {
    int len1 = s1.length();
    int len2 = s2.length();
    int dp[2][len2 + 1];
    memset(dp, 0, sizeof(dp));
    for(int i = 0; i < len1; ++i) {
      for(int j = 1; j <= len2; ++j) {
        int parity = i & 1;
        dp[parity][j] = max(dp[!parity][j], dp[parity][j - 1]);
        if(s2[j - 1] == s1[i]) {
          dp[parity][j] = max(dp[parity][j], dp[!parity][j - 1] + 1);
        }
      }
    }
    return dp[!(len1 & 1)][len2];
  }
public:
  int minDistance(string s1, string s2) {
    return s1.length() + s2.length() - LCS(s1, s2) * 2;
  }
};

// Accepted
// 1306/1306 cases passed (17 ms)
// Your runtime beats 77.81 % of cpp submissions
// Your memory usage beats 99.74 % of cpp submissions (6.4 MB)