Codeforces 339
2013-09-01 09:31
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这是一场5道题都写不到1K的CF。
A:
题意是排序。
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A:
题意是排序。
#include<cstdio> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; int n,z[1010],l[4],r[4]; bool check() { for (int a=1;a<=n;a++) if (z[a]!=a) return false; return true; } bool dfs(int x) { if (check()) { printf("%d\n",x-1); for (int a=x-1;a>0;a--) printf("%d %d\n",l[a],r[a]); return true; } if (x>3) return false; for (int a=1;a<=n;a++) if (z[a]!=a) { l[x]=a; for (int b=a+1;;b++) if (z[b]==a) { r[x]=b; reverse(z+a,z+b+1); if (dfs(x+1)) return true; reverse(z+a,z+b+1); break; } break; } for (int a=n;a>=1;a--) if (z[a]!=a) { r[x]=a; for (int b=a-1;;b--) if (z[b]==a) { l[x]=b; reverse(z+b,z+a+1); if (dfs(x+1)) return true; reverse(z+b,z+a+1); break; } break; } return false; } int main() { scanf("%d",&n); for (int a=1;a<=n;a++) scanf("%d",&z[a]); dfs(1); return 0; }
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