题目:
You are given two arrays (without duplicates) nums1
and nums2
where nums1
’s elements are subset of nums2
. Find all the next greater numbers for nums1
's elements in the corresponding places of nums2
.
The Next Greater Number of a number x in nums1
is the first greater number to its right in nums2
. If it does not exist, output -1 for this number.
Example 1:
Input: nums1 = [4,1,2], nums2 = [1,3,4,2].
Output: [-1,3,-1]
Explanation:
For number 4 in the first array, you cannot find the next greater number for it in the second array, so output -1.
For number 1 in the first array, the next greater number for it in the second array is 3.
For number 2 in the first array, there is no next greater number for it in the second array, so output -1.
Example 2:
Input: nums1 = [2,4], nums2 = [1,2,3,4].
Output: [3,-1]
Explanation:
For number 2 in the first array, the next greater number for it in the second array is 3.
For number 4 in the first array, there is no next greater number for it in the second array, so output -1.
Note:
- All elements in
nums1
andnums2
are unique. - The length of both
nums1
andnums2
would not exceed 1000.
代码:
自己的:
class Solution {
public:
vector<int> nextGreaterElement(vector<int>& findNums, vector<int>& nums) {
vector<int> result;
int s1 = findNums.size();
int s2 = nums.size();
bool b = 0;
for (int i=0; i<s1; i++){
int tem = -1;
for (int j=0; j <s2; j++){
if (findNums[i] == nums[j]){
for (int k=j; k<s2; k++){
if (nums[k]>findNums[i]){
tem = nums[k];
break;
}
}
}
}
result.push_back(tem);
}
return result;
}
};
别人的:
class Solution {
public:
vector<int> nextGreaterElement(vector<int>& findNums, vector<int>& nums) {
stack<int> s;
unordered_map<int,int> hash;
for(int i=0;i<nums.size();i++){
if(s.empty()){
s.push(nums[i]);
}
else if(nums[i] > s.top()){
while(!s.empty() && s.top()<nums[i]){
hash[s.top()] = nums[i];
s.pop();
}
s.push(nums[i]);
}
else s.push(nums[i]);
}
while(!s.empty()){
hash[s.top()] = -1;
s.pop();
}
vector<int> res;
for(int i=0;i<findNums.size();i++){
res.push_back(hash[findNums[i]]);
}
return res;
}
};
unordered_map类是c++11标准的内容,具体介绍见链接:https://msdn.microsoft.com/zh-cn/library/bb982522.aspx