1 public class _003TwoSum { 2  3     public static void main(String[] args) { 4         int a[]={3,22,4,7,8,22}; 5          6         display(twoSum3(a,30)); 7     } 8     　　//暴力搜索法 9      public static int[] twoSum(int[] numbers, int target) {10           int index[] = {0,0};  11             for(int i=0; i<numbers.length; i ++){  12                 for(int j=i+1; j<numbers.length; j++){  13                     if(target == numbers[i]+numbers[j]){  14                         index[0] = i+1;  15                         index[1] = j+1;  16                         return index;  17                     }  18                 }  19             }  20             return index;  21                 22         }23 24      //使用map，因为刚好是两个值，一个值一个下表map刚好可以储存然后用map的containsKey的方法 25      public static  int[] twoSum2(int[] numbers, int target) {26             int index[] = {0,0};27             HashMap<Integer, Integer> num = new HashMap<Integer,Integer>();28             for(int i=0;i<numbers.length;i++){29                 num.put(numbers[i], i);30             }31             for(int i=0;i<numbers.length;i++){32                 int temp = target-numbers[i];33                 if(num.containsKey(temp)&&i<num.get(temp)){34                     index[0] = i+1;35                     index[1] = num.get(temp)+1;36                     break;37                 }38             }39             return index;40         }41      42      43      public static void display(int a[])44      {45          for(int i=0;i<a.length;i++)46              System.out.println(a[i]);47      }48      49      50    86 }