After much thought, I title it as "Day0" but not "Day1". This is not purely out of the custom of a CS student, also, it is because I regard it as an informal one and a simple test. (I have to admit that there is a little prejudice for zero.Hah~)
Now, I am ready to plant a flag that I will solve at least one problem a day on Leetcode for next several(?) months. If, though I truly hope I can stick to this and publish everyday, if there is emergency, I will make up on other idle time！
Today's problem is really a simple one. But in contrast, the top solution given by the website is a beautiful one. And the top solution only run 8 ms, which really surprised me.
O(n) VS O(n*n)? To be honest, I don't know much of how to compute the complexity of the algorithm. ->_->
public static int[] twoSum(int[] nums, int target) {
int [] a=new int [2];
for(int i=0;i<nums.length-1;i++){
for(int j=i+1;j<nums.length;j++){
if(nums[i]+nums[j]==target){
a[0]=i;
a[1]=j;
}
}
}
return a;
}
public static int[] twoSumTop(int[] nums, int target) {
int [] a=new int [2];
Map<Integer, Integer> map=new HashMap<Integer,Integer>();
for(int i=0;i<nums.length;i++){
if(map.containsKey(target-nums[i])){
a[0]=map.get(target-nums[i]);
a[1]=i;
return a;
}
map.put(nums[i], i);
}
return a;
}