72. Edit Distance 编辑距离

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)

You have the following 3 operations permitted on a word:

a) Insert a character
b) Delete a character
c) Replace a character

给定两个单词word1和word2，找到将word1转换为word2所需的最小步数。 （每个操作都算作1步。） 

你有一个单词允许以下3个操作： 

a）插入一个字符

b）删除一个字符 

c）替换一个字符

/**
 * @param {string} word1
 * @param {string} word2
 * @return {number}
 */
var minDistance = (word1, word2) => {
    let lenA = word1.length;
    let lenB = word2.length;
    let d = createMatrix(lenB + 1, lenA + 1);
    for (let i = 0; i <= lenA; i++) {
        d[i][0] = i;
    }
    for (let i = 0; i <= lenB; i++) {
        d[0][i] = i;
    }
    for (let i = 1; i <= lenA; i++) {
        for (let j = 1; j <= lenB; j++) {
            if (word1[i - 1] == word2[j - 1]) {
                d[i][j] = d[i - 1][j - 1];
            } else {
                d[i][j] = Math.min(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + 1);
            }
        }
    }
    return d[lenA][lenB];
}
let createMatrix = (rowNum, colNum) => {
    let matrix = [];
    matrix.length = colNum;
    for (let i = 0; i < matrix.length; i++) {
        matrix[i] = [];
        matrix[i].length = rowNum;
        matrix[i].fill(0);
    }
    return matrix
}
let a = "abcde";
let b = "abcd";
console.log(minDistance(a, b));

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