在nums = [2,4,6,8,10,12] 中寻找 target = 10
mid = (0 + 5) >> 1 = 2 target = nums[2] = 6
6 < 10
left = 3 right = 5
mid = (3 + 5) >> 1 = 4 target = nums[4] = 10
在nums = [2,4,6,8,10,12] 中寻找 target = 4
mid = (0 + 5) >> 1 = 2 target = nums[2] = 6
6 > 4
left = 0 right = 1
mid = (0 + 1) >> 1 = 0 target = nums[0] = 2
2 < 4
left = 1 right = 1
mid = (1 + 1) >> 1 = 1 target = nums[0] = 4
