count_problems.js

// frog river one
function solution(X,A){
  const AL = A.length;
  const positionSet = new Set();
  for (let i = 0; i < AL; i++){
    positionSet.add(A[i]);
    if(positionSet.size === X){
      return i;
    }
  }
  return -1;
}


//permCheck
function solution(A){
  const setCheck = new Set(A);
//   const n = A.length;

//   // 计算预期的等差数列和（从 1 到 n）
//   const expectedSum = (n * (Math.min(...A) + Math.max(...A))) / 2;
//   const actualSum = A.reduce((sum,num) =>{sum + num}, 0);
//   if ( setCheck.size === A.length && expectedSum === actualSum &&Math.max(...A) === n && Math.min(...A) === 1){
//     return 1;
//   }
  const n = A.length;

  if (setCheck.size === n && Math.max(...A) === n && Math.min(...A) === 1) {
    return 1;
  } else {
    return 0;
  }
return 0;
}

//maxCounters
function solution(N,A){
  let result = new Array(N).fill(0);
  let maxCounter =0;
  let lazyMax = 0;
  for(let i =0; i < A.length; i++){
    if(A[i] === N +1){
       result = result.map(() => maxCounter);
    //   maxCounter = Math.max(lazyMax,maxCounter);
    } else if (1 <= A[i] && A[i]<= N){
      result[A[i]-1] += 1;
      maxCounter = Math.max(result[A[i] -1], maxCounter);
      }
    }
    return result;
  }

  //Missing Integer(brute force)
  function solution(A){
    let misInt = 1;
    let maxInt = -1;
    const removeNeg = A.filter(x => x > 0);

  //Missing Integer(brute force)
  function solution(A){
    let misInt = 1;
    let maxInt = -1;
    const removeNeg = A.filter(x => x >= 0);

    // const removeRepeat =  new Set(A);
    if (removeNeg.length > 1){
        for( let i = 0; i <  removeNeg.length -1; i++){
            if(removeNeg[i] <= removeNeg[i+1]){
                maxInt = Math.max(maxInt,removeNeg[i+1]);
                misInt = maxInt + 1;
            } else {
                maxInt = removeNeg[i];
                misInt = maxInt + 1;
            }
        }
    }else if (removeNeg.length === 1 ){
        misInt = removeNeg[0] + 1;
    }
    return misInt;
  }