import java.util.HashMap;

//bruse force

public class P0001_twoSum1 {

public int[] twoSum(int[] nums, int target) {

int[]res=new int[2];

for(int i=0;i<nums.length;i++){

for(int j=i+1;j<nums.length;j++){

if(nums[i]+nums[j]==target){

res[0]=i;

res[1]=j;

return res;

}

}

}

return null;

}

//hashmap

public int[]twosum(int[]nums,int target) {

HashMap<Integer,Integer> map=new HashMap<>();

int[]res=new int[2];

for(int i=0;i<nums.length;i++){

if(map.containsKey(target-nums[i])){

res[0]=map.get(target-nums[i]);

res[1]=i;

return res;

}

else{

map.put(nums[i],i);

}

}

return null;

}

}

/*

P0001_twoSum1 p = new P0001_twoSum1(); 类的实例化

P0001_twoSum1 p1=new P0001_twoSum1();

int[] res = p.twoSum(new int[] {2,7,11,15}, 9); //调用函数 传入的数组声明+初始化，要有类型方括号初始值

int[]res1=p.twosum(new int[]{3,5,7,4}, 12);

for (int i : res1) { java里数组不能直接打印，需要借助for将数组里的元素呈现出来

System.out.println(i);

}

for(int j:res){

System.out.println(j);

}

*/