import java.util.HashMap;
//法1：哈希表
class Solution {
public int[] twoSum(int[] numbers, int target) {
HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
for(int i = 0; i < numbers.length; i++) {
if (map.containsKey(target - numbers[i])) {
return new int[] {map.get(target - numbers[i]) + 1, i + 1};
} else {
map.put(numbers[i], i);
}
}
return new int[] {-1, -1};
}
}
复制代码
//法2：双指针
class Solution {
public int[] twoSum(int[] numbers, int target) {
int l = 0;
int r = numbers.length-1;
// l不能取等于r，因为不能取重复的元素
while(l<r){
int sum = numbers[l]+numbers[r];
if(sum == target){
return new int[]{l+1,r+1};
}else if(sum>target){
r--;
}else{
l++;
}
}
return new int[]{-1,-1};
}
}