贪心 UVALive 6832 Bit String Reordering

 

题目传送门

 1 /*  2  贪心：按照0或1开头，若不符合，选择后面最近的进行交换。然后选取最少的交换次数  3 */  4 #include <cstdio>  5 #include <algorithm>  6 #include <cstring>  7 #include <string>  8 #include <cmath>  9 #include <vector> 10 #include <map> 11 #include <queue> 12 using namespace std; 13 14 const int MAXN = 22 + 10; 15 const int INF = 0x3f3f3f3f; 16 int a[MAXN], b[MAXN], c[MAXN]; 17 18 int main(void) //UVALive 6832 Bit String Reordering 19 { 20 // freopen ("A.in", "r", stdin); 21 22 int n, m; 23 while (scanf ("%d%d", &n, &m) == 2) 24  { 25 for (int i=1; i<=n; ++i) {scanf ("%d", &a[i]); c[i] = a[i];} 26 for (int i=1; i<=m; ++i) scanf ("%d", &b[i]); 27 28 int cnt1 = 0, cnt2 = 0; int now = 0; int p = 0; 29 bool ok1 = true, ok2 = true; 30 for (int i=1; i<=m && ok1; ++i) 31  { 32 for (int j=1; j<=b[i]; ++j) 33  { 34 if (a[p+j] != now) 35  { 36 int k = p + j; 37 while (k <= n && a[k] != now) k++; 38 if (k == n+1 || a[k] != now) {ok1 = false; break;} 39 cnt1 += k - (p + j); 40 swap (a[k], a[p+j]); 41  } 42  } 43 p += b[i]; now = 1 - now; 44  } 45 46 now = 1; p = 0; 47 for (int i=1; i<=m && ok2; ++i) 48  { 49 for (int j=1; j<=b[i]; ++j) 50  { 51 if (c[p+j] != now) 52  { 53 int k = p + j; 54 while (k <= n && c[k] != now) k++; 55 if (k == n+1 || c[k] != now) {ok2 = false; break;} 56 cnt2 += k - (p + j); 57 swap (c[p+j], c[k]); 58  } 59  } 60 p += b[i]; now = 1 - now; 61  } 62 63 // printf ("%d %d\n", cnt1, cnt2); 64 if (!ok1) printf ("%d\n", cnt2); 65 else if (!ok2) printf ("%d\n", cnt1); 66 else printf ("%d\n", min (cnt1, cnt2)); 67  } 68 69 return 0; 70 }