JavaScript搜索算法：线性查找、二分查找

线性查找

function LinerSearch(arr, target) {// 设置目标元素位置let position &＃61; -1;let len &＃61; arr.length;for (let i &＃61; 0; i < len; i&＃43;&＃43;) {if (arr[i] &＃61;&＃61;&＃61; target) {position &＃61; i;return position;}}return position;
}console.log(&＃39;LinerSearch&＃39;, LinerSearch([4, 18, 5, 2, 9, 2], 9))


二分查找

function binarysearch(arr, target) {// 前提为有序数组if (Array.isArray(arr)) {let len &＃61; arr.length; //数组长度let maxIndex &＃61; len - 1;let minIndex &＃61; 0;while (minIndex <&＃61; maxIndex) {let midIndex &＃61; Math.floor((maxIndex &＃43; minIndex) / 2); //向下取整// 判断目标值与中间值比较if (target < arr[midIndex]) {// 重置设置最大值索引maxIndex &＃61; midIndex - 1;} else if (target > arr[midIndex]) {minIndex &＃61; midIndex &＃43; 1} else if (target &＃61;&＃61;&＃61; arr[midIndex]) {return arr[midIndex]}}// 查找失败return -1;}
}console.log(&＃39;binarysearch&＃39;, binarysearch([3, 6, 7, 15, 18, 19], 6));


二分查找递归实现

function recursionBinarySearch(arr, target, minIndex, maxIndex) {if (Array.isArray(arr)) {let len &＃61; arr.length;let max &＃61; maxIndex || len - 1;let min &＃61; minIndex || 0;let midIndex &＃61; Math.floor((max &＃43; min) / 2)if (min > max) {return -1; //查找失败}if (target > arr[midIndex]) {min &＃61; midIndex &＃43; 1return recursionBinarySearch(arr, target, min, max)} else if (target < arr[midIndex]) {max &＃61; midIndex - 1return recursionBinarySearch(arr, target, min, max)} else if (target &＃61;&＃61;&＃61; arr[midIndex]) {return midIndex}}
}console.log(&＃39;recursionBinarySearch&＃39;, recursionBinarySearch([3, 6, 7, 15, 18, 19], 7))