KD树，这东西其实在ML经常被使用，不过30s的时限还是第一次见。
1 /* 2966 */ 2 #include <iostream> 3 #include <string> 4 #include <map> 5 #include <queue> 6 #include <stack> 7 #include <set> 8 #include <vector> 9 #include <algorithm> 10 #include <cstdio> 11 #include <cmath> 12 #include <ctime> 13 #include <cstring> 14 #include <climits> 15 #include <cctype> 16 using namespace std; 17 18 typedef struct { 19 int x, y; 20 } Point_t; 21 22 typedef struct { 23 int axis; 24 Point_t p; 25 int l, r; 26 } node_t; 27 28 const int maxn = 1e5+5; 29 Point_t P[maxn], P2[maxn]; 30 node_t nd[maxn]; 31 int L; 32 __int64 ans; 33 34 __int64 Eucl(Point_t a, Point_t b) { 35 return 1LL*(a.x-b.x)*(a.x-b.x) + 1LL*(a.y-b.y)*(a.y-b.y); 36 } 37 38 bool compx(const Point_t &a, const Point_t &b) { 39 return a.x < b.x; 40 } 41 42 bool compy(const Point_t &a, const Point_t &b) { 43 return a.y < b.y; 44 } 45 46 void newNode() { 47 ++L; 48 nd[L].l = nd[L].r = 0; 49 } 50 51 int create_KD(int l, int r, int d) { 52 if (l > r) 53 return 0; 54 newNode(); 55 int rt = L; 56 nd[rt].axis = d&1; 57 if (l == r) { 58 nd[rt].p = P[l]; 59 return rt; 60 } 61 if (d & 1) 62 sort(P+l, P+r+1, compy); 63 else 64 sort(P+l, P+r+1, compx); 65 int mid = (l+r)>>1; 66 nd[rt].p = P[mid]; 67 nd[rt].l = create_KD(l, mid-1, d+1); 68 nd[rt].r = create_KD(mid+1, r, d+1); 69 return rt; 70 } 71 72 void cal(int rt, Point_t p) { 73 if (rt == 0) 74 return ; 75 int i, j, k; 76 77 __int64 d = Eucl(nd[rt].p, p); 78 if (d && d<ans) 79 ans = d; 80 81 if (nd[rt].axis) { 82 j = nd[rt].p.y; 83 k = p.y; 84 } else { 85 j = nd[rt].p.x; 86 k = p.x; 87 } 88 89 if (k <= j) 90 cal(nd[rt].l, p); 91 else 92 cal(nd[rt].r, p); 93 94 if (1LL*(j-k)*(j-k) < ans) { 95 if (k <= j) 96 cal(nd[rt].r, p); 97 else 98 cal(nd[rt].l, p); 99 } 100 } 101 102 int main() { 103 int t, n; 104 int i, j, k; 105 106 #ifndef ONLINE_JUDGE 107 freopen("data.in", "r", stdin); 108 freopen("data.out", "w", stdout); 109 #endif 110 111 scanf("%d", &t); 112 while (t--) { 113 scanf("%d", &n); 114 for (i=0; i<n; ++i) { 115 scanf("%d %d", &P[i].x, &P[i].y); 116 P2[i] = P[i]; 117 } 118 L = 0; 119 int rt = create_KD(0, n-1, 0); 120 for (i=0; i<n; ++i) { 121 ans = LLONG_MAX; 122 cal(rt, P2[i]); 123 printf("%I64d ", ans); 124 } 125 } 126 127 #ifndef ONLINE_JUDGE 128 printf("time = %d ", (int)(clock())); 129 #endif 130 131 return 0; 132 }