LeetCode:496. 下一个更大元素 I

class Solution {

public:

vector<int> nextGreaterElement(vector<int>& nums1, vector<int>& nums2) {

vector<int>greater=nextGreaterElement(nums2);

unordered_map<int,int>greaterMap;

for(int i=0;i<nums2.size();i++){

greaterMap[nums2[i]]=greater[i];

}

vector<int>res(nums1.size());

for(int i=0;i<nums1.size();i++){

res[i]=greaterMap[nums1[i]];

}

return res;

}

vector<int> nextGreaterElement(vector<int>& nums){

int n=nums.size();

vector<int>res(n);

stack<int> s;

for(int i=n-1;i>=0;i--){

while(!s.empty()&&s.top()<=nums[i]){

s.pop();

}

res[i]=s.empty()?-1:s.top();

s.push(nums[i]);

}

return res;

}

};