数据有两组漏了一个数，所以在读入之前要先赋值为0。
1 #include<cstdio> 2 #include<algorithm> 3 #define MAXN 100010 4 #define INF 0x7FFFFFFF 5 using namespace std; 6 struct SpalyTree { 7 int size, root; 8 int next[MAXN][2], pre[MAXN], key[MAXN]; 9 void Init() { 10 size = root = 0; 11 } 12 void NewNode(int &rt, int father, int val) { 13 rt = ++size; 14 next[rt][0] = next[rt][1] = 0; 15 pre[rt] = father; 16 key[rt] = val; 17 } 18 void Rotate(int x, int kind) { 19 int y = pre[x]; 20 pre[next[x][kind]] = y; 21 next[y][!kind] = next[x][kind]; 22 if (pre[y]) 23 next[pre[y]][next[pre[y]][1] == y] = x; 24 pre[x] = pre[y]; 25 next[x][kind] = y; 26 pre[y] = x; 27 } 28 void Splay(int x, int goal) { 29 while (pre[x] != goal) { 30 if (next[pre[x]][0] == x) 31 Rotate(x, 1); 32 else 33 Rotate(x, 0); 34 } 35 if (!goal) 36 root = x; 37 } 38 bool Insert(int k) { 39 int x, y; 40 for (x = root; next[x][k > key[x]]; x = next[x][k > key[x]]) { 41 if (k == key[x]) { 42 Splay(x, 0); 43 return false; 44 } 45 } 46 NewNode(next[x][k > key[x]], x, k); 47 Splay(next[x][k > key[x]], 0); 48 return true; 49 } 50 int GetPre() { 51 int x = next[root][0]; 52 if (x) { 53 while (next[x][1]) 54 x = next[x][1]; 55 return key[x]; 56 } 57 return INF; 58 } 59 int GetNext() { 60 int x = next[root][1]; 61 if (x) { 62 while (next[x][0]) 63 x = next[x][0]; 64 return key[x]; 65 } 66 return INF; 67 } 68 }; 69 SpalyTree tree; 70 int main() { 71 int n, ans, x, a, b; 72 while (~scanf("%d%d", &n, &ans)) { 73 tree.Init(); 74 tree.NewNode(tree.root, 0, ans); 75 while (--n) { 76 x = 0; 77 scanf("%d", &x); 78 if (tree.Insert(x)) { 79 a = tree.GetPre(); 80 if (a < INF) 81 a = x - a; 82 b = tree.GetNext(); 83 if (b < INF) 84 b -= x; 85 ans += min(a, b); 86 } 87 } 88 printf("%d\n", ans); 89 } 90 return 0; 91 }