拼多多暑期笔试

选择题

一道网络判断。

两道前端。

1.js

class Parent {
  constructor(name) {
    this.name = name;
  }
  logName() {
    console.log(this.name);
  }
}
class Child extends Parent {
  constructor(name) {
    super(name + "_P");
    this.name = name + "_C";
  }
  logName = () => {
    super.logName();
    console.log(this.name);
  };
  log() {
    this.logName();
    console.log(this.name);
  }
}

const child = new Child("A");
const obj = {
  name: "object",
  log: child.log,
  logName: child.logName,
};
obj.log();

2.js

const p1 = new Promise((resolve) => setTimeout(() => resolve(1), 0));
const p2 = new Promise((_, reject) => setTimeout(() => reject(2), 0));

Promise.allSettled([p1, p2])
  .then(([res1, res2]) => {
    console.log(res1.value + res2.value);
  })
  .catch((err) => {
    console.log(err.value);
  });

setTimeout(() => {
  console.log(3);
}, 0);

Promise.resolve()
  .then(() => {
    console.log(4);
  })
  .then(() => {
    console.log(5);
  });

setTimeout(() => {
  console.log(6);
}, 0);

编程题

传入一个 config 判断是否存在循环依赖。

3.js

function hasCycleDep(config) {
  const visited = [];
  let queue = [];
  for (const key in config) {
    if (queue.includes(key)) queue = queue.filter((item) => item !== key);
    visited.push(key);
    const { deps } = config[key];
    for (const dep of deps) {
      if (visited.includes(dep)) return true;
      queue.push(dep);
    }
  }
  return false;
}

const result = hasCycleDep({
  a: { deps: ["b", "d"] },
  b: { deps: ["c"] },
  c: { deps: ["a"] },
});
console.log(result);

蛇形输出矩阵，交叉进行从左下到右上和从右上到左下的遍历。

4.js

function matrixSnakeTraversal(matrix) {
  const srcX = 0;
  const srcY = 0;

  const result = [];

  const rows = matrix.length;
  const columns = matrix[0].length;

  while (result.length < rows * columns) {
    up(srcX, srcY, result, rows, columns, matrix);
  }

  return result;
}
function up(srcX, srcY, result, rows, columns, matrix) {
  while (srcX >= 0 && srcY < columns) {
    result.push(matrix[srcX--][srcY++]);
  }
  if (srcY >= columns) {
    srcX += 2;
    srcY--;
  } else if (srcX < 0) {
    srcX++;
  }
  down(srcX, srcY, result, rows, columns, matrix);
}
function down(srcX, srcY, result, rows, columns, matrix) {
  while (srcX < rows && srcY >= 0) {
    result.push(matrix[srcX++][srcY--]);
  }
  if (srcX >= rows) {
    srcX--;
    srcY += 2;
  } else if (srcY < 0) {
    srcY++;
  }
  up(srcX, srcY, result, rows, columns, matrix);
}

const matrix = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9],
  [11, 12, 13],
];

console.log(matrixSnakeTraversal(matrix));

我的做法爆栈了，下面附一个修正的：

5.js

function matrixSnakeTraversal2(matrix) {
  let srcX = 0;
  let srcY = 0;
  const result = [];

  const rows = matrix.length;
  const columns = matrix[0].length;

  while (result.length < rows * columns) {
    [srcX, srcY] = up2(srcX, srcY, result, rows, columns, matrix);
    if (result.length < rows * columns) {
      [srcX, srcY] = down2(srcX, srcY, result, rows, columns, matrix);
    }
  }

  return result;
}

function up2(srcX, srcY, result, rows, columns, matrix) {
  while (srcX >= 0 && srcY < columns) {
    result.push(matrix[srcX][srcY]);
    srcX--;
    srcY++;
  }
  // 处理边界
  if (srcY >= columns) {
    srcX += 2;
    srcY--;
  } else if (srcX < 0) {
    srcX++;
  }
  return [srcX, srcY];
}

function down2(srcX, srcY, result, rows, columns, matrix) {
  while (srcX < rows && srcY >= 0) {
    result.push(matrix[srcX][srcY]);
    srcX++;
    srcY--;
  }
  // 处理边界
  if (srcX >= rows) {
    srcX--;
    srcY += 2;
  } else if (srcY < 0) {
    srcY++;
  }
  return [srcX, srcY];
}

// 测试矩阵
const matrix2 = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9],
  [11, 12, 13],
];

console.log(matrixSnakeTraversal2(matrix2));

实现一个带优先级的 Promise 异步队列，可以添加、执行、暂停、恢复、得到最终结果。
6.js
js
```
class PriorityPromiseQueue {
  add() {}
  start() {}
  pause() {}
  resume() {}
  getAllResults() {}
}
```
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拼多多暑期笔试 ​

选择题 ​

编程题 ​

拼多多暑期笔试

选择题

编程题