25_December.cpp

    long long int MissingNo(vector<vector<int> >& matrix) {
        // Code here
        int n = matrix.size(),k,l;
        vector<long long int> row(n,0),col(n,0);
        long long int d1=0,d2=0,temp,ele;
        for(int i=0;i<n;i++){
            long long int sum=0;
            for(int j=0;j<n;j++){
                sum+=matrix[i][j];
                if(matrix[i][j]==0){
                    k=i;
                    l=j;
                }
                col[j]+=matrix[i][j];
            }
            row[i]=sum;
        }
        if(k==0){
            temp=row[1];
        }
        else{
            temp=row[0];
        }
        for(int i=0;i<n;i++){
            if(i==k){
                ele = temp-row[i];
            }
            else if(row[i]!=temp)return -1;
        }
        for(int i=0;i<n;i++){
            if(i==l){
                if(ele+col[i]!=temp)return -1;
            }
            else if(col[i]!=temp)return -1;
        }
        for(int i=0;i<n;i++){
            d1+=matrix[i][i];
            d2+=matrix[i][n-1-i];
            if(matrix[i][i]==0){
                d1+=ele;
            }
            if(matrix[i][n-1-i]==0){
                d2+=ele;
            }
        }
        if((d1!=temp) or (d2!=temp) or (ele<=0))return -1;
        return ele;
    }