归并排序
示意图
实现
function mergeSort(arr) {
const len = arr.length
if (len < 2) {
return arr
}
const middle = Math.floor(len/2)
const left = arr.slice(0, middle)
const right = arr.slice(middle)
return merge(mergeSort(left), mergeSort(right))
}
function merge(arrA, arrB) {
let lenA = arrA.length, i = 0
let lenB = arrB.length, j = 0
const result = []
while (i < lenA && j < lenB) {
if (arrA[i] > arrB[j]) {
result.push(arrB[j++])
} else {
result.push(arrA[i++])
}
}
while (i < lenA) {
result.push(arrA[i++])
}
while (j < lenB) {
result.push(arrB[j++])
}
return result
}
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