Serpentine filling number

test questions C Snake fill in

【 Problem description 】

As shown in the figure below , Xiao Ming uses from 1 A positive integer at the beginning “ Serpentine ” Fill an infinite matrix .

It is easy to see that the number in the second row and second column of the matrix is 5. Please calculate the number... In the matrix 20 Xing di 20 What's the number of columns ？

【 Answer submission 】

This is a question to fill in the blanks , You just need to work out the results and submit them . The result of this question is one
It's an integer , Only fill in the whole number when submitting the answer , Fill in the extra content will not be able to score .

answer ：761

#include <iostream>
using namespace std;
int a[100][100];
int main()
{
    
    int t = 1;
    //  Current state  0 It's down  1 It's going up 
    int f = 1;
    int i, j;
    i = j = 1;
    while (i < 50)
    {
    
        a[i][j] = t++;
        //  If you get to the top   And the current state is on the rise   That means it needs to be lowered 
        if (i - 1 <= 0 && f)
        {
    
            j++;
            f = 0;
            continue;
        }
        else if (j - 1 <= 0 && !f) //  ditto 
        {
    
            i++;
            f = 1;
            continue;
        }
        //  Two actions to control ascent and descent 
        if (f)
            i--, j++;
        else
            i++, j--;
    }
    cout << a[20][20];
    return 0;
}