2389. Longest Subsequence With Limited Sum.cpp

/*
You are given an integer array nums of length n, and an integer array queries of length m.

Return an array answer of length m where answer[i] is the maximum size of a subsequence that you can take from nums such that the sum of its elements is less than or equal to queries[i].

A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.

 

Example 1:

Input: nums = [4,5,2,1], queries = [3,10,21]
Output: [2,3,4]
Explanation: We answer the queries as follows:
- The subsequence [2,1] has a sum less than or equal to 3. It can be proven that 2 is the maximum size of such a subsequence, so answer[0] = 2.
- The subsequence [4,5,1] has a sum less than or equal to 10. It can be proven that 3 is the maximum size of such a subsequence, so answer[1] = 3.
- The subsequence [4,5,2,1] has a sum less than or equal to 21. It can be proven that 4 is the maximum size of such a subsequence, so answer[2] = 4.
Example 2:

Input: nums = [2,3,4,5], queries = [1]
Output: [0]
Explanation: The empty subsequence is the only subsequence that has a sum less than or equal to 1, so answer[0] = 0.
 

Constraints:

n == nums.length
m == queries.length
1 <= n, m <= 1000
1 <= nums[i], queries[i] <= 106
*/



class Solution {
public:
    int binary_search(vector<int> arr, int t, int i, int j){
        int ans = -1;
        while(i<=j){
            int mid = i + (j-i)/2;
            if(arr[mid]<=t){
                ans = mid;
                i = mid+1;
            }else{
                j = mid-1;
            }
        }
        return ans;
    } 
    vector<int> answerQueries(vector<int>& nums, vector<int>& queries) {
        sort(nums.begin(), nums.end());
        int n = nums.size();
        vector<int> arr(n+1, 0);
        for(int i=1;i<=n;i++){
            arr[i] = nums[i-1]+arr[i-1];
        }

        vector<int> ans;
        int l=0, h=n;
        for(int i=0;i<queries.size();i++){
            int x = binary_search(arr, queries[i], l, h);
            ans.push_back(x);
        }
        return ans;
    }
};