OJ---两数之和

第一种：暴力解法，双for循环遍历。当数组量太大时会超时

public int[] twoSum (int[] numbers, int target) {
        // write code here
        int temp;
        int twoSum[] = new int[2];
        for(int i=0;i<numbers.length;i++){
            for(int j=i+1;j<numbers.length;j++){
                temp = numbers[i]+numbers[j];
                if(temp==target){
                    twoSum[0] = i+1;
                    twoSum[1] = j+1;
                }
            }
        }
        return twoSum;
    }

第二种：使用HashMap处理

public int[] twoSum (int[] numbers, int target) {
        // write code here
        int twoSum[] = new int[2];
        int temp;
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < numbers.length; i++) {
            temp = target - numbers[i];
            if (map.containsKey(temp)) {
                twoSum[0] = map.get(temp) + 1;
                twoSum[1] = i + 1;
            } else {
                map.put(numbers[i], i);
            }
        }
        return twoSum;
    }