Longest common substring

lcs.ts

function Int2DArray(a: number, b: number) {
  const data = new Int32Array(a * b);
  return {
    set(i: number, j: number, v: number) {
      const index = j * a + i;
      data[index] = v;
    },
    get(i: number, j: number) {
      const index = j * a + i;
      return data[index];
    }
  }
}

export function LCSubstr(s: string,t: string) {
  const r = s.length;
  const n = t.length;
  const L = Int2DArray(r, n);
  // size of longest common substring
  let z = 0;
  // last index of matched string
  let ret = new Int16Array(Math.ceil(Math.min(r, n) / 2));
  let cur = 0;
  for (let i = 0; i < r; ++i) {
    for (let j = 0; j < n; ++j) {
      if (s[i] === t[j]) {
        if (i === 1 || j === 1) {
          L.set(i, j, 1);
        } else {
          L.set(i, j, L.get(i - 1, j - 1) + 1);
        }
        if (L.get(i, j) > z){
          z = L.get(i, j);
          cur = 0;
          ret[cur] = i;
        } else if (L.get(i, j) === z){
          cur += 1;
          ret[cur] = i;
        }
      } else {
        L.set(i, j, 0);
      }
    }
  }
  cur += 1;
  const substrings = [];
  for (let i = 0; i < cur; ++i) {
    substrings.push(s.substr(ret[i] - z, z + 1));
  }
  return substrings;
}

console.log(LCSubstr("ABABC", "BABCA"));