Introduction
Alternatively, see comments above each method for details about functionality.
I completely stole one method from someone (ily nate c)
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import java.lang.*;
import java.util.*;
import java.lang.Math;
class FunWith2DArrays
{
/*
* preCondition : isArrow[i].length == isArrow[k].length for all i, k, 0 < i,j < isArrow.length
* isArrow.length > 0 && isArrow[0].length > 0
*
* postCondition: returns true if the 2D array is a square array (same number of rows and columns)
* and the 2d array contains zeros in all entries except the first row,
* first column and the main diagonal
*/
public boolean isArrowHeadArray( int[] [] isArrow)
{
if(isArrow.length!=isArrow[0].length)
{
return false;
}
for(int r = 0; r<isArrow.length; r++)
{
for(int c = 0; c<isArrow.length; c++)
{
if(r!=c && r!=0 && c!=0)
{
if(isArrow[r][c]!=0)
{
return false;
}
}
if(isArrow[0][c]==0 || isArrow[r][0]==0 || isArrow[r][r]==0 )
{
return false;
}
}
}
return true;
}
/*
* preCondition : gpa[j].length == gpa[k].length for 0 <= j, k < gpa.length
* gpa.length > 0 && gpa[0].length > 0
*
*
* postcondition : returns true if mgp is as Generalized Permutation Matrix with integer entries
* that is, returns true iff the following conditions are true
* 1) All entries in the Matrix are integers
* since you are being passed an int[][], you do not need to test this condition
* 2) there is exactly one nonzero entry in each row and each column.
* The nonzero entry can be any nonzero value (e.g., a positive or negative int)
* 3) The array is a square array (number of rows == number of columns)
*/
public boolean isIntegerGeneralizedPermutationArray(int[][] gpa){
int i,j;
for(int r=0;r<gpa.length;r++){
i=0;
for(int c=0;c<gpa[0].length;c++){
if(gpa[r][c]!=0)
i++;
if(r==0){
j=0;
for(int rr=0;rr<gpa.length;rr++)
if(gpa[rr][c]!=0)
j++;
if(j!=1)
return false;
}
}
if(i!=1)
return false;
}
return true;
}
/*
* preCondition : ma[i].length == ma[k].length for all i, k, 0 <= i,j < ma.length
* ma.length > 0 && ma[0].length > 0
*
* Do NOT assume the 2d array is a square array
* That is, ma.length may not be equal to ma[0].length
*
* postcondition : returns true if ma is a Monge Matrix
* A m-by-n matrix is said to be a Monge array if for all i, j, k, p
* with 0 <= i K k < m and 0 <= j < p < n
* and ma[i][j] + ma[k][p] <= ma[i][p] + ma[k][j]
*/
public boolean isMongeArray(int[][] ma){
for(int i=0; i<ma.length; i++){
for(int j=0; j<ma[i].length; j++){
try{
if( ma[i][j] + ma[i+1][j+1] > ma[i][j+1] + ma[i+1][j] ){
return false;
}
}catch(Exception e){}
}
}
return true;
}
}