uva524 (Dfs water problem)

Test instructions

The beads numbered 1 to N, strung into a bracelet, require any two adjacent beads and are prime numbers;

Ideas:

Data volume only 16, hit a quality tables, direct DFS search on the line;

#include <cstdio> #include <cstring> #include <algorithm>using namespace Std;int vis[32];int viss[20] ; int res[20],n;void init () {vis[1] = 1;for (int i = 2; I <= 31;i++) {if (!vis[i]) {for (int j = i + i; j <=; J + = i) VIS[J] = 1;}} return;} void dfs (int pre,int sum) {if (sum = = N) {if (!vis[pre + 1]) {printf ("%d", res[1]), for (int i = 2; I <= n;i++) {printf ("%d ", Res[i]);} printf ("\ n");} return;}  for (int i = 1; I <= n; i++) {if (!viss[i] &&!vis[i + pre]) {Viss[i] = 1;res[sum + 1] = I;dfs (i,sum + 1); Viss[i] = 0;}} return;} int main () {int cas = 1;init (); bool F = 0;while (scanf ("%d", &n) = = 1) {if (f) printf ("\ n"); Elsef = 1;memset (Viss, 0,sizeo F (viss));p rintf ("Case%d:\n", cas++); viss[1] = 1;res[1] = 1;dfs (all);}}

uva524 (Dfs water problem)