使用动态规划解答相关题目

编辑距离【leetcode-72】

题目描述

给定两个字符串，求解通过插入或者替换是两个字符串相同的最小步骤

运行效率

代码如下

function minDistance(word1: string, word2: string): number {
  if (!word2 || !word1) return word2.length || word1.length;
  const dp = initDp();
  getMinDistance(word1.length, word2.length);
  return dp[word1.length][word2.length];

  function getMinDistance(i: number, j: number) {
    const lMin = dp[i - 1][j] ?? getMinDistance(i - 1, j);
    const tMin = dp[i][j - 1] ?? getMinDistance(i, j - 1);
    const ltMin = dp[i - 1][j - 1] ?? getMinDistance(i - 1, j - 1);
    if (word1.charAt(i - 1) === word2.charAt(j - 1)) {
      dp[i][j] = Math.min(lMin + 1, tMin + 1, ltMin);
    } else {
      dp[i][j] = Math.min(lMin, tMin, ltMin) + 1;
    }
    return dp[i][j];
  }

  function initDp() {
    return new Array(word1.length + 1).fill(0).map((item, index) => {
      const temp = [];
      if (index === 0) {
        for (let i = 0; i <= word2.length; i++) temp[i] = i;
      } else {
        temp.push(index);
      }
      return temp;
    });
  }
}

const res = minDistance("horse", "ros");
debugger;