프로그래머스 68645: 삼각 달팽이

#include <vector>
#define SOUTH 0
#define EAST 1
#define NORTHWEST 2
using namespace std;

vector<int> solution(int n) {
	vector<int> answer;
	vector<vector<int>> arr(n + 1, vector<int>(n + 1));

	int i, j;
	int direction, nowR, nowC;

	i = 1, nowR = 1, nowC = 1;
	arr[nowR++][nowC] = i++;
	direction = SOUTH;

	while (i <= n * (n + 1) / 2) {
		if (direction == SOUTH) {
			while (nowR <= n && arr[nowR][nowC] == 0) {
				arr[nowR++][nowC] = i++;
			}
			nowR--;
			nowC++;
			direction = EAST;
		}
		if (direction == EAST) {
			while (nowC <= nowR && arr[nowR][nowC] == 0) {
				arr[nowR][nowC++] = i++;
			}
			nowC--;
			nowR--;
			nowC--;
			direction = NORTHWEST;
		}
		if (direction == NORTHWEST) {
			while (1 <= nowR && nowR <= n && 1 <= nowC && nowC <= nowR && arr[nowR][nowC] == 0) {
				arr[nowR--][nowC--] = i++;
			}
			nowR++;
			nowC++;
			nowR++;
			direction = SOUTH;
		}
	}

	for (i = 1; i <= n; i++) {
		for (j = 1; j <= i; j++) answer.push_back(arr[i][j]);
	}
	return answer;
}