Algo_1_vector

#include <bits/stdc++.h>
 
using namespace std;
class Solution
{
public:
    vector<vector<int>> merge(vector<vector<int>> &intervals)
    {
        sort(intervals.begin(), intervals.end(), [](vector<int> &a, vector<int> &b)
             { return a[0] < b[0]; });
 
        vector<vector<int>> megred;
        vector<int> prev = intervals[0];
        for (int i = 1; i < intervals.size(); i++)
        {
            vector<int> interval = intervals[i];
            if (interval[0] <= prev[1])
            {
                prev[1] = max(prev[1], interval[1]);
            }
            else
            {
                megred.push_back(prev);
                prev = interval;
            }
        }
        megred.push_back(prev);
        return megred;
    }
};

#include <bits/stdc++.h>
using namespace std;
 
class Solution
{
public:
    vector<int> productExceptSelf(vector<int> &nums)
    {
        int n = nums.size();
        vector<int> pre(n);
        vector<int> suf(n);
        pre[0] = 1;
        suf[n - 1] = 1;
        for (int i = 1; i < n; i++)
        {
            pre[i] = pre[i - 1] * nums[i - 1];
        }
 
        for (int i = n - 2; i >= 0; i--)
        {
            suf[i] = suf[i + 1] * nums[i + 1];
        }
        vector<int> ans(n);
        for (int i = 0; i < n; i++)
        {
            ans[i] = pre[i] * suf[i];
        }
        return ans;
    }
};

#include <bits/stdc++.h>
 
using namespace std;
class Solution
{
public:
    vector<int> result;
    int n, m = 0;
 
    vector<int> spiralOrder(vector<vector<int>> &matrix)
    {
        n = matrix.size();
        m = matrix[0].size();
        int top = 0, bottom = n - 1;
        int left = 0, right = m - 1;
        vector<int> v;
        while (top <= bottom && left <= right)
        {
            for (int i = left; i <= right; i++)
            {
                v.push_back(matrix[top][i]);
            }
            top++;
            for (int i = top; i <= bottom; i++)
            {
                v.push_back(matrix[i][right]);
            }
            right--;
            if (top <= bottom)
            {
                for (int i = right; i >= left; i--)
                {
                    v.push_back(matrix[bottom][i]);
                }
                bottom--;
            }
            if (left <= right)
            {
                for (int i = bottom; i >= top; i--)
                {
                    v.push_back(matrix[i][left]);
                }
                left++;
            }
        }
        return v;
    }
};
 

#include <bits/stdc++.h>
 
using namespace std;
class Solution
{
public:
    void rotate(vector<vector<int>> &matrix)
    {
        int n = matrix.size();
        for (int i = 0; i < n; i++)
        {
            for (int j = i + 1; j < n; j++)
            {
                swap(matrix[i][j], matrix[j][i]);
            }
        }
 
        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < n / 2; j++)
            {
                swap(matrix[i][j], matrix[i][n - j - 1]);
            }
        }
    }
};