#include <iostream>
#include <fstream>
#include <string>

using namespace std;

// This program reads in a 2D description of elevations.
// Each elevation is an integer between 1 and 9, for simplicity
// It then simulates a lava flow from (row,col).
// In particular, lava flows from a point to any other adjacent point
// WITH THE SAME ELEVATION or less.
// The program then prints out a "map" showing what got scorched by lava.

int** readMapFromFile (string filename, int &numRows, int &numCols);
void  printMap  (int **map, int numRows, int numCols);
void  doLavaFlow(int **map, int numRows, int numCols, int row, int col, int elevation);
bool  inBounds  (int numRows, int numCols, int row, int col);


int main() {
    int numRows, numCols;
    int **map = readMapFromFile("map.txt", numRows, numCols);

    printMap(map, numRows, numCols);

    // Ask user for where lava flow is
    int row, col;
    char junk;
    cout << "Enter flow start location like (3,0): ";
    cin  >> junk >> row >> junk >> col >> junk;

    // Simulate lava flow
    // For simplicity, we set the elevation of each "scorched" location to 0.
    // This function requires that we provide the starting elevation
    int elevation = map[row][col];
    doLavaFlow(map, numRows, numCols, row, col, elevation);

    // print out everywhere that got scorched
    printMap(map, numRows, numCols);

    return 0;
}


// Assume a lava flow is entering (row,col) from an elevation of "inElevation".
// If (row,col) has a greater elevation, the lava flow is stopped.  
// Otherwise, (row,col) gets scorched and lava may flow up, down, left, and right from this cell.
// Every "scorched" cell gets set to an elevation of zero.
void  doLavaFlow(int **map,
				 int numRows, 
				 int numCols, 
				 int row, 
				 int col, 
				 int inElevation)
{
	//base case
	//check for in bounds
	if (row < 0 || row >= numRows || col < 0 || col >= numCols)
		return;

	int myElevation = map[row][col];

	//higher elevation, stop the lava
	if (myElevation > inElevation)
	{
		return;
	}

	//if already schorched, no need to do it again
	if (myElevation == 0)
	{
		return;
	}

	//else, set elevation to 0 
	map[row][col] = 0;
	
	//recursive case
    // Lava can flow from this point, at this elevation, to four surrounding areas.
    doLavaFlow(map, numRows, numCols, row-1, col, myElevation);
	doLavaFlow(map, numRows, numCols, row+1, col, myElevation);
	doLavaFlow(map, numRows, numCols, row, col-1, myElevation);
	doLavaFlow(map, numRows, numCols, row, col+1, myElevation);

	return;
}