面试高频手撕代码题

数组去重

• 借助栈的方法

let quCh = arr => {
  let res = [];
  while (arr.length > 0) {
    let item = arr.shift();
    res.indexOf(item) === -1 && res.push(item);
  }
  return res;
};
console.log(quCh([1, 4, 5, 6, 6, 7, 7, 999, 999, 8, 7, 999]));

• set 方法

function quCh(arr) {
  return [...new Set(arr)];
}

console.log(quCh([1, 2, 2, 3, 4, 4]));

• indexOf() + lastIndexOf()方法

let quCh = arr => {
  let result = [];
  arr.forEach((item, index) => {
    if (arr.indexOf(item, index) === arr.lastIndexOf(item) && result.indexOf(item) === -1) {
      result.push(item);
    }
  });
  return result;
};

let arr = [1, 4, 5, 6, 6, 7, 7, 999, 999, 8, 7, 999];
console.log(quCh(arr));

• 循环

function quCh(arr) {
  arr.sort((a, b) => a - b);
  let res = [];
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] !== arr[i - 1]) {
      res.push(arr[i]);
    }
  }
  return res;
}

console.log(quCh([1, 2, 2, 3, 3, 4, 3, 5, 5]));

• includes()方法

function quCh(arr) {
  let res = [];
  arr.forEach(item => {
    if (!res.includes(item)) {
      res.push(item);
    }
  });
  return res;
}

console.log(quCh([1, 2, 3, 4, 3, 3, 3, 7, 6, 6, 9, 9]));