主要内容：Leetcode-JAVA版，参考：leetcode，LeetCode All in One 题目讲解汇总
1.Two Sum
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, and you may not use the same element twice.
Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].
给定一个array和一个数，输出两个数相加和为给定数的下标
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package com.zhang.sfa;
import java.util.HashMap;
public class {
public int[] twoSum(int[] nums, int target) {
HashMap<Integer, Integer> m = new HashMap<Integer, Integer>();
int[] res = new int[2];
for (int i = 0; i < nums.length; ++i) {
if (m.containsKey(target - nums[i])) {
res[0] = i;
res[1] = m.get(target - nums[i]);
break;
}
m.put(nums[i], i);
}
return res;
}
public static void main(String[] args) {
int[] nums = {2, 7, 11, 15};
int target = 9;
Two_Sum sum=new Two_Sum();
int[] result=sum.twoSum(nums, target);
for (int element: result) {
System.out.println(element);
}
}
}
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2.Add Two Numbers
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