The Worm Turns

worm.cpp

#include <stdio.h>
#include <string.h>
#include <list>
#include <iostream>
#include <sstream>
using namespace std;

typedef struct point{
    int row, col;
} point;

bool ranToSelf(std::list<point> snakeRep){
    point head = snakeRep.front();
    int eqCount = 0;

    for(std::list<point>::iterator it = snakeRep.begin(); it != snakeRep.end(); it++){
        if((*it).row == head.row && (*it).col == head.col){
            eqCount++;
        }
    }

    return eqCount == 2;
}

bool ranOffBoard(std::list<point> snakeRep){
    point head = snakeRep.front();
    return 0 >= head.row || head.row > 50 || 0 >= head.col || head.col > 50;
}

std::string move_snake(std::string movestring){
    std::list<point> snakeRep;

    for(int i = 30; i >= 11; i--){
        point p;
        p.row = 25;
        p.col = i;
        snakeRep.insert(snakeRep.end(), p);
    }

    int moveCounter = 1;

    for(std::string::iterator it = movestring.begin(); it != movestring.end(); it++){
        // Move the tail
        snakeRep.pop_back();
        // Get the head
        point head = snakeRep.front();
        point newHead;
        newHead.row = -1;
        newHead.col = -1;
        switch(*it){
            case 'N':
                newHead.row = head.row - 1;
                newHead.col = head.col;
                break;
            case 'E':
                newHead.col = head.col + 1;
                newHead.row = head.row;
                break;
            case 'W':
                newHead.col = head.col - 1;
                newHead.row = head.row;
                break;
            case 'S':
                newHead.row = head.row + 1;
                newHead.col = head.col;
                break;
        }
        snakeRep.push_front(newHead);

        if(ranToSelf(snakeRep)){
            std::stringstream ss;
            ss << moveCounter;
            return "The worm ran into itself on move " + ss.str() + ".\n";
        } else if(ranOffBoard(snakeRep)){
            std::stringstream ss;
            ss << moveCounter;
            return "The worm ran off the board on move " + ss.str() + ".\n";
        }

        moveCounter++;
    }
    std:: stringstream ss;
    ss << moveCounter;
    return "The worm successfully made all " + ss.str() + " moves.\n";

}

int main(){
    int moveLength;
    cin >> moveLength;

    while(moveLength != 0){
        std::string moveString;
        cin >> moveString;
        cout << move_snake(moveString);
        cin >> moveLength;
    }

    return 0;
}