Title Link

Title Analysis

Simple simulation questions

Solving problems

1. Traverse 1-sqrt(N) to get the closest m, n (M > n)
2. Clockwise rotation:
Looking for the law, every time we reach the border, we actually turn to be certain,
Record the current running direction and change the direction at the boundary

Attention points
At the beginning of initialization of two-dimensional array, I want to save some time. Write it as fill(vis[0], vis[0]+(N+1)*(n+1), false)
In fact, it does not strictly assign values to the small matrices to be used, and it will go down line by line, so there is an error;

AC program (C + +)

/**********************************
*@ID: 3stone
*@ACM: PAT.A1105 Spiral Matrix
*@Time: 18/9/20
*@IDE: VScode 2018 + clang++ 
***********************************/
#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
#include<cmath>
using namespace std;
const int maxn = 1010;

int N;
int matrix[maxn][maxn];
bool vis[maxn][maxn]; //Is the tag filled with numbers
priority_queue<int> Q; //Store data for heap sorting

void find_matrix(int& n, int& m) {
	int sqt = (int)sqrt((1.0) * N);
	for(int i = sqt; i>= 1; i--) {
		if(N % i == 0) {
			n = i;
			break;
		}
	}
	m = N / n;
}

//Determine whether the direction needs to be changed
void judgeDirection(int& i, int& j, int& direction, int n, int m) {
	
	switch(direction) {
	case 1:
		j--;//go left
		if(j < 0 || vis[i][j] == true) { //frontier or used
			j++; //recover
			i--; direction = 3; //true on
		}
		break; 
	case 2:
		j++;//go right
		if(j >= n || vis[i][j] == true) { 
			j--;
			i++; direction = 4; //turn down
		}
		break;
	case 3:
		i--; //go up
		if (i < 0 || vis[i][j] == true) {
			i++;
			j++; direction = 2; //turn right
		}
		break;
	case 4:
		i++; // go down
		if(i >= m || vis[i][j] == true) {
			i--;
			j--; direction = 1; //true on
		}
		break;
	//default:
	}//switch

}

int main() {
	int n, m, temp;
	while(scanf("%d", &N) != EOF) {
		for(int i = 0; i < N; i++) {
			scanf("%d", &temp); 
			Q.push(temp);
		} 

		//fill(vis[0], vis[0] + maxn * maxn, false); / / Yes, the array is not large
		for(int i = 0; i < m; i++)
			fill(vis[i], vis[i] + n, false);

		//find m and n 
		find_matrix(n, m);
		
		//how to intial the matrix clockwisely
		int direction = 2; //go right at first
		int i = 0, j = 0;
		while(!Q.empty()) {
			matrix[i][j] = Q.top();
			Q.pop();
			
			vis[i][j] = true;
			//Directions 1, 2, 3 and 4 represent left, right, up and down respectively
			judgeDirection(i, j, direction, n, m);

		}//while

		//output the matrix
		for(int i = 0; i < m; i++) {
			for(int j = 0; j < n - 1; j++) {
				printf("%d ", matrix[i][j]);
			}
			printf("%d\n", matrix[i][n - 1]);
		}

	}//while-scanf

	return 0;
}