Algorithmic competition Getting Started classic example 3-2 snake fill number

In the n*n phalanx filled with,?, n*n, asked to fill the snake. For example n=4 when the Phalanx is

10 11 12 1

9 16 13 2

8 15 14 3

7 6 5 4

Above the square, the extra space is only to facilitate the observation of the law, do not have to strictly output. N≤8.

#include <stdio.h> #include <stdlib.h> #include <string.h> #define MAXN 10int A[maxn][maxn];int Main (  int argc, char *argv[]) {int n, count = 1;  int x, y;  scanf ("%d", &n);  memset (A, 0, sizeof (a)); x = 0;  y = n-1;    A[x][y] = 1; while (Count < N*n) {while (X+1<n &&!a[x+1][y]) a[++x][y] = ++count;//a[x++][y] Details determine success or failure, so that x changes the W     Hile (y-1>=0 &&!a[x][y-1]) a[x][--y] = ++count;     while (x-1>=0 &&!a[x-1][y]) a[--x][y] = ++count;       while (Y+1<n &&!a[x][y+1]) a[x][++y] = ++count;     } for (x = 0; x < n; + +) {for (y = 0; y < n; y++) printf ("%3d", A[x][y]);  printf ("\ n");     }/* while (Count <= n*n) {while (x < n-1 &&!a[x][y]) {A[x][y] = count; x + +; count++;}     while (Y > 0 &&!a[x][y]) {A[x][y] = count; y--; count++;}     while (x > 0 &&!a[x][y]) {A[x][y] = count; x--; count++;} while (Y < n-1 &&!a[x][y]) {A[x][y] = CounT y++; count++;     }} for (x = 0; <= n-1; x + +) {for (y = 0; y< n-1; y++) printf ("%d", a[x][y]);    printf ("%d\n", A[x][y]);  } */System ("PAUSE"); return 0;}

Summary: 1 Determine whether to cross the border and determine whether to fill in the numbers

2 boundary conditions,> or >= etc., first judgment, after X, y changes

3 x + + also changes, keep in mind

4 A[0][3] It was assigned at the beginning.

Algorithmic competition Getting Started classic example 3-2 snake fill number