TypeScript declare Set Array type All In One

TypeScript declare Set Array type All In One

error

Type 'unknown' is not assignable to type 'number'.

function singleNumber(nums: number[]): number {
  const set = new Set();
  for(let i = 0; i < nums.length; i ++) {
    if(set.has(nums[i])) {
      set.delete(nums[i]);
    } else {
      set.add(nums[i]);
    }
  }
  for(let item of set) {
    return item;
  }
};

Type 'Set<unknown>' is missing the following properties from type 'number[]': length, pop, push, concat, and 23 more.(2740)

function singleNumber(nums: number[]): number {
  const set: number[] = new Set();
  for(let i = 0; i < nums.length; i ++) {
    if(set.has(nums[i])) {
      set.delete(nums[i]);
    } else {
      set.add(nums[i]);
    }
  }
  for(let item of set) {
    return item;
  }
};

solution ✅

const set = new Set<number>();

function singleNumber(nums: number[]): number {
  // const set: number[] = new Set();
  const set = new Set<number>();
  for(let i = 0; i < nums.length; i ++) {
    if(set.has(nums[i])) {
      set.delete(nums[i]);
    } else {
      set.add(nums[i]);
    }
  }
  for(let item of set) {
    return item;
  }
  // return [...set][0] as number;
};

refs

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