Two Sum-Notzuonotdied - LinkWorld Algorithm Blog

今天随机到的比较简单，先打卡一波。

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].

answer:

Kotlin

class Solution {
    fun twoSum(nums: IntArray, target: Int): IntArray {
        for (i in nums.indices) {
            for (j in nums.indices) {
                if (i == j) continue
                if (nums[i] == target - nums[j]) {
                    return intArrayOf(i, j)
                }
            }
        }
        return intArrayOf(0, 0)
    }
}

fun main(args: Array<String>) {
    print(Solution().twoSum(intArrayOf(2, 7, 11, 15), 9).asList())
}

C++

public int[] twoSum(int[] nums, int target) {
    Map<Integer, Integer> map = new HashMap<>();
    for (int i = 0; i < nums.length; i++) {
        int complement = target - nums[i];
        if (map.containsKey(complement)) {
            return new int[] { map.get(complement), i };
        }
        map.put(nums[i], i);
    }
    throw new IllegalArgumentException("No two sum solution");
}