Rotated Array Search

rotated-array-search.js

const search = function pivotSearch(nums, target) {
  // track sub array start & end
  let leftIdx = 0;
  let rightIdx = nums.length - 1;

  while (rightIdx >= leftIdx) {
    const midIdx = ((rightIdx + leftIdx) / 2) | 0;
    const midNum = nums[midIdx];
    if (target === midNum) return midIdx;

    const rightNum = nums[rightIdx];
    const pivotRight = rightNum - midNum < 0;

    if (
      (pivotRight && (target <= rightNum || target >= midNum))
      || (!pivotRight && target <= rightNum && target >= midNum)
    ) {
      // search right half
      leftIdx = midIdx + 1;
    } else {
      // search left half
      rightIdx = midIdx - 1;
    }
  }

  return -1;
};

// target = 1;
// [6, 7, 0, 2, 3, 4, 5];
// [3, 4, 5, 6, 7, 0, 2];

const testArr = [4, 5, 6, 7, 0, 1, 2];
// const testArr = [0, 2];
console.log(search(testArr, 6));