/*
question -> https://leetcode.com/problems/product-of-array-except-self/description/
*/

//code:
class Solution {
public:
    vector<int> productExceptSelf(vector<int>& a) {
        int n=a.size();
        vector<int> ans(n);
        int p=1;
        for(int i=0;i<n;i++){
            ans[i]=p;
            p=(p*a[i]);
        }
        p=1;
        for(int i=n-1;i>=0;i--){
            ans[i]*=p;
            p=(p*a[i]);
        }
        return ans;
    }
};






/*
question link-> https://leetcode.com/problems/check-knight-tour-configuration/
*/


//code:


class Solution {
public:
    bool can_go(int s,int e, map<int,pair<int,int>>& m){
        pair<int,int> p1=m[s],p2=m[e];
        int y1=p1.first,x1=p1.second,y2=p2.first,x2=p2.second;
        if(abs(x2-x1)==1&&abs(y2-y1)==2) return true;

        if(abs(x2-x1)==2&&abs(y2-y1)==1) return true;
        return false;
    }
    bool checkValidGrid(vector<vector<int>>& grid) {
        int n=grid.size();
        map<int,pair<int,int>> m;
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                m[grid[i][j]]={i,j};
            }
        }
        pair<int,int> tempp={0,0};
        if(m[0]!=tempp) return false;

        int temp=(n*n)-1;
        for(int i=0;i<=(temp-1);i++){
            if(can_go(i,i+1,m)) continue;
            else return false;
        }
        return true;
    }
};