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LeetCode 1 Two Sum 题解

1.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].

题意：

输入一个数组，一个目标数据，返回这个数组里两个相加可以得这个数据的下标。

2.解题思路:

见代码。

3.代码

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public class Solution {
    public int[] twoSum(int[] nums, int target) {
        int[] ans = new int[2];

		ArrayList<Integer> list = new ArrayList<Integer>();
		for (int i : nums) {
			list.add(i);
		}
		for (int i = 0; i < nums.length; i++) {
			if (list.contains(target - nums[i])) {
				int j = list.indexOf(target - nums[i]);
				if (i == j)
					continue;
				// System.out.println(i+"  "+j);
				if (i < j) {
					ans[0] = i;
					ans[1] = j;
				} else {
					ans[0] = j;
					ans[1] = i;
				}
				return ans;
			}
		}
		return ans;
    }
}

4.一些总结：