Lower and Upper Bound (std::lower_bound)

Medium STL Algorithms

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Problem Statement

Write a C++ program using `std::lower_bound` to find the first position where a value can be inserted in a sorted vector without violating order.

Input Format

First line: N and Target. Second line: N sorted integers.

Output Format

Print index of lower bound.

Constraints

1 <= N <= 1000

Sample Input

5 30
10 20 30 40 50

Sample Output

Explanation

Binary search utilities `lower_bound` and `upper_bound` locate insertion boundaries in $O(log N)$ time.

Starter Code

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    int n, target;
    if (std::cin >> n >> target) {
        std::vector<int> vec(n);
        for (int i = 0; i < n; i++) std::cin >> vec[i];
        
        // Write your std::lower_bound logic here

    }
    return 0;
}

Limits

Time Limit: 1s
Memory Limit: 256MB

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