KMP算法JavaScript实现笔记

function kmp(strs1, strs2) {
  if (strs1 === strs2 || !strs2) return 0;
  const sLen = strs1.length,
    tLen = strs2.length;
  const next = Array(tLen);
  next[0] = 0;
  let matchLen = 0;
  for (let curIndex = 1; curIndex < tLen; curIndex++) {
    while (matchLen && strs2[curIndex] !== strs2[matchLen]) {
      matchLen = next[matchLen - 1];
    }
    if (strs2[curIndex] === strs2[matchLen]) {
      matchLen++;
    }
    next[curIndex] = matchLen;
  }
  matchLen = 0;
  for (let curIndex = 0; curIndex < sLen; curIndex++) {
    while (matchLen && strs1[curIndex] !== strs2[matchLen]) {
      matchLen = next[matchLen - 1];
    }
    if (strs1[curIndex] === strs2[matchLen]) {
      matchLen++;
    }
    if (matchLen === tLen) return curIndex - tLen + 1;
  }
  return -1;
}
console.log(kmp("ABABCABAA", "AA"));