Concise JAVA DP solution with comments


  • 12
    public int minDistance(String word1, String word2) {
    	// dp[i][j] : minimum steps to convert i long word1 and j long word2
    	int dp[][] = new int[word1.length() + 1][word2.length() + 1];
    
    	for (int i = 0; i <= word1.length(); i++) dp[i][0] = i;    	
    	for (int j = 0; j <= word2.length(); j++) dp[0][j] = j; 
    	 
    	for (int i = 1;i <= word1.length(); i++) {
    		for (int j = 1; j<= word2.length(); j++) {
    			if (word1.charAt(i-1) == word2.charAt(j-1))// <--
    				dp[i][j] = dp[i-1][j-1];
    			else 
                    // dp[i-1][j-1] : replace word1(i) with word2(j), because word1(0, i-1) == word2(0, j-1);
                    // dp[i  ][j-1] : delete word(j)
                    // dp[i-1][j  ] : delete word(i), because word1(0, i-1) == word2(0, j)
    				dp[i][j] = Math.min(dp[i-1][j-1], Math.min(dp[i][j-1], dp[i-1][j])) + 1; 
    		}
    	}
    	return dp[word1.length()][word2.length()];
    }

  • 0
    H

    Clear code and good comments! Nice work!


  • 0
    V

    Your comments make your solution much easier to understand. 1000 times better than those pure coding without any explanation. Thanks !


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