Answer 1

// 一个O(n) 的解法，在排序的基础上做二路归并。
var num1 = [1, 2, 5, 7, 10];
var num2 = [3, 4, 5, 6, 8, 9];
console.log(findMedian(num1, num2));
function findMedian(arr1, arr2) {
	var arr = [];
	if (arr1[0] >= arr2[arr2.length - 1]) {
		arr = [...arr2, ...arr1];
	} else if (arr1[arr1.length - 1] <= arr2[0]) {
		arr = [...arr1, ...arr2];
	} else {
		var arr_i = 0;
		var arr1_i = 0;
		for (var arr2_i = 0; arr2_i < arr2.length; arr2_i ++) {
			if (arr1[arr1_i] < arr2[arr2_i]) {
				arr[arr_i] = arr1[arr1_i];
				arr_i ++;
				arr1_i ++;
				arr2_i --;
			} else {
				arr[arr_i] = arr2[arr2_i];
				arr_i ++;
			}
		}
		if (arr2_i == arr2.length) {
			for (var i = arr1_i; i < arr1.length; i ++) {
				arr[arr_i] = arr1[i];
				arr_i ++;
			}
		} else {
			for (var i = arr2_i; i < arr2.length; i ++) {
				arr[arr_i] = arr2[i];
				arr_i ++;
			}
		}
	}
	if (arr.length % 2 == 0) {
		return (arr[Math.floor((arr.length - 1) / 2)] + arr[Math.floor(arr.length / 2)]) / 2;
	} else {
		return arr[Math.floor(arr.length / 2)];
	}
}