二分法查找 js 算法

 

let arr = [0, 1, 2, 4, 5, 6, 7, 8]; let arr2 = [88, 77, 66, 55, 44, 33, 22, 11]; BinarySearch(arr2, 77); BinarySearch(arr, 2); function BinarySearch(arr, target) { let s = 0; let e = arr.length - 1; let m = Math.floor((s + e) / 2); let sortTag = arr[s] <= arr[e];//确定排序顺序 while (s < e && arr[m] !== target) { if (arr[m] > target) { sortTag && (e = m - 1); !sortTag && (s = m + 1); } else { !sortTag && (e = m - 1); sortTag && (s = m + 1); } m = Math.floor((s + e) / 2); } if (arr[m] == target) { console.log('找到了,位置%s', m); return m; } else { console.log('没找到'); return -1; } }