Spiral Matrix (25)

1105. Spiral Matrix (25)

好久没有更新博客了，因为一直在实习，呜呜：

具体题目如下：
This time your job is to fill a sequence of N positive integers into a spiral matrix in non-increasing order. A spiral matrix is filled in from the first element at the upper-left corner, then move in a clockwise spiral. The matrix has m rows and n columns, where m and n satisfy the following: m*n must be equal to N; m>=n; and m-n is the minimum of all the possible values.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N. Then the next line contains N positive integers to be filled into the spiral matrix. All the numbers are no more than 104. The numbers in a line are separated by spaces.

Output Specification:

For each test case, output the resulting matrix in m lines, each contains n numbers. There must be exactly 1 space between two adjacent numbers, and no extra space at the end of each line.

Sample Input:
12
37 76 20 98 76 42 53 95 60 81 58 93
Sample Output:
98 95 93
42 37 81
53 20 76
58 60 76

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• 题目具体分析
  题目本身不是很难，意思特别容易理解，难点在于怎么进行clockwise spiral.应该是翻译为顺时针螺旋排列把，其实又不是排序，而是排列。不过这个排列是在排序的基础上进行的。
• 1
  对输入的N个数字，找出合适的输出数组大小。输出数组是这样的，行列的乘积==N，行数大于等于列数。一定要看清是行数大于或者等于列数。我就是记成了行数不能等于列数，（_哭哭）。对于求对应的行数和列数，只要简单的两重循环求进行了，不会超时的。
• 2
  数组排序。=，C++数组排序调用系统的sort函数即可，Java更简单，Arrays.sort。不过，150ms,Java肯定超时。这里有一个小技巧，碰到小于400ms的直接选择C或者C++，Java一般不用想了，而且特殊情况。当然很少了。
  3
  clockwise spiral 顺时针螺旋排列，这个是本题最麻烦的，我一次写也不会，是参考了，别人写的。其实，就是从左往右，从上往下，从右往左，从下往上四大块内容，知道这个就so easy啦~ 这里，也要注意一下，在while(true)里面结束的条件，是index==-1啦。
• 具体代码如下啦

---

#include <iostream>
#include <algorithm>
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;
int main(int argc, char *argv[]) {
	int N;
	cin>>N;
	int num[N];
	int m = 2;
	int n = 1;
	int min = N;
	int row=0,col=0;
	for(int k=0;k<N;k++){
		cin>>num[k];
	}
	if(N==1){
		cout<<num[0]<<endl;
	}
	else{
	
	for(n=1;n<=N;n++){
		for(m=n;m<=N;m++){
			if(m*n==N){
				if(m-n<min){
					min = m-n;
					row = m;
					col = n;
				}
			}
		}
	}
	
	sort(num,num+N);
	int result[row][col];
	for(int k=0;k<row;k++){
		for(int p=0;p<col;p++){
			result[k][p] = -1;
		}
	}
	int index = N-1;
	//cout<<row<<" "<<col<<endl;
	int row1 = 0,row2 = row-1,col1= 0,col2 = col-1;
	while(true){
//		从左往右
		for(int i=col1;i<=col2;i++){
			result[row1][i] = num[index--];
			//cout<<"["<<row1<<","<<i<<"]"<<endl; 
		}
		if(index==-1)
		break;
//		cout<<index<<endl; 
//		从上往下 
		row1++;
		for(int i=row1;i<=row2;i++){
			result[i][col2] = num[index--]; 
			//cout<<"["<<i<<","<<col2<<"]"<<endl; 
		}
		if(index==-1)
		break;
//		从右往左 
		col2--;
		for(int i=col2;i>=col1;i--){
			result[row2][i] = num[index--]; 
			//cout<<"["<<row2<<","<<i<<"]"<<endl;
		}
			if(index==-1)
		break;
//		
//		 从下往上 
		row2--;
		for(int i=row2;i>=row1;i--){
			result[i][col1] = num[index--];
			//cout<<"["<<i<<","<<col1<<"]"<<endl;
		}
		col1++;
			if(index==-1)
		break;
}

		for(int i=0;i<row;i++){
			cout<<result[i][0];
		for(int j=1;j<col;j++){
			cout<<" "<<result[i][j];
		}
		cout<<endl;
	}
	}
	return 0;
}