LeetCode ---- Two Sum (Java Lua 实现)

题目：

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

UPDATE (2016/2/13):

The return format had been changed to zero-based indices. Please read the above updated description carefully.

Java 实现：

public class Solution {
    public int[] twoSum(int[] nums, int target) {
        int[] result = null;
        for (int i = 0; i < nums.length; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[i] + nums[j] == target) {
                    result = new int[2];
                    result[0] = i;
                    result[1] = j;
                }

            }
        }
        return result;
    }
}

Lua 实现：

function twoSum(nums, target)
        assert(type(nums) == "table", "nums 不是 table 类型")
        assert(type(target) == "number", "target 不是 数字")
        for i = 1, #nums do
            for j = i + 1, #nums+1 do
                if (nums[i] + nums[j] == target) then
                    return {i, j}

                end
            end
        end
end


nums = {1,2,3,4,5,6,7,8,9}
target = 10
result = twoSum(nums,target)
print(result[1])
print(result[2])

因为主要是为了练习 Lua 的语法，所以说一下在写过程经常遗漏的东西：

• Lua 数组下标是从 1 开始的，而 Java 是从 0 开始的，笔者没注意还是用 0 导致执行报错（lua: twoSum.lua:18: attempt to perform arithmetic on field '?' (a nil value) stack traceback:  twoSum.lua:18: in main chunk  [C]: ? ）
• for 和 if 后面有 do 关键字