好久没做过三分的题目了。
1 /* 4355 */ 2 #include <iostream> 3 #include <sstream> 4 #include <string> 5 #include <map> 6 #include <queue> 7 #include <set> 8 #include <stack> 9 #include <vector> 10 #include <deque> 11 #include <algorithm> 12 #include <cstdio> 13 #include <cmath> 14 #include <ctime> 15 #include <cstring> 16 #include <climits> 17 #include <cctype> 18 #include <cassert> 19 #include <functional> 20 #include <iterator> 21 #include <iomanip> 22 using namespace std; 23 //#pragma comment(linker,"/STACK:102400000,1024000") 24 25 #define sti set<int> 26 #define stpii set<pair<int, int> > 27 #define mpii map<int,int> 28 #define vi vector<int> 29 #define pii pair<int,int> 30 #define vpii vector<pair<int,int> > 31 #define rep(i, a, n) for (int i=a;i<n;++i) 32 #define per(i, a, n) for (int i=n-1;i>=a;--i) 33 #define clr clear 34 #define pb push_back 35 #define mp make_pair 36 #define fir first 37 #define sec second 38 #define all(x) (x).begin(),(x).end() 39 #define SZ(x) ((int)(x).size()) 40 #define lson l, mid, rt<<1 41 #define rson mid+1, r, rt<<1|1 42 43 typedef struct { 44 double x, w; 45 } node_t; 46 47 const double eps = 1e-4; 48 const int maxn = 50005; 49 node_t nd[maxn]; 50 int n; 51 52 double calc(double x) { 53 double ret = 0.0; 54 55 rep(i, 0, n) 56 ret += pow(fabs(x-nd[i].x), 3) * nd[i].w; 57 58 return ret; 59 } 60 61 void solve() { 62 double l = 1e7; 63 double r = -1e7; 64 double m1, m2; 65 double tmp1, tmp2; 66 67 rep(i, 0, n) { 68 l = min(l, nd[i].x); 69 r = max(r, nd[i].x); 70 } 71 72 while (fabs(r-l) > eps) { 73 m1 = l + (r-l)/3; 74 m2 = r - (r-l)/3; 75 tmp1 = calc(m1); 76 tmp2 = calc(m2); 77 if (tmp1 < tmp2) { 78 r = m2; 79 } else if (tmp1 > tmp2) { 80 l = m1; 81 } else { 82 l = r; 83 } 84 } 85 86 double ans = calc(l); 87 printf("%.0lf ", ans); 88 } 89 90 int main() { 91 ios::sync_with_stdio(false); 92 #ifndef ONLINE_JUDGE 93 freopen("data.in", "r", stdin); 94 freopen("data.out", "w", stdout); 95 #endif 96 97 int t; 98 99 scanf("%d", &t); 100 rep(tt, 1, t+1) { 101 scanf("%d", &n); 102 rep(i, 0, n) 103 scanf("%lf %lf", &nd[i].x, &nd[i].w); 104 printf("Case #%d: ", tt); 105 solve(); 106 } 107 108 #ifndef ONLINE_JUDGE 109 printf("time = %d. ", (int)clock()); 110 #endif 111 112 return 0; 113 }