两数之和
class Solution {
private Map<Integer, Integer> map = new HashMap<Integer, Integer>();
public int[] twoSum(int[] nums, int target) {
if (nums == null || nums.length < 2) {
return null;
}
int i = 0;
map.put(nums[i], i);
for (i = 1; i < nums.length; i ++) {
int number = nums[i];
Object index = map.get(target - number);
if (index != null) {
return new int[] {(int) index, i};
}
map.put(number, i);
}
return null;
}
}
