81 lines
1.8 KiB
C++
81 lines
1.8 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <cmath>
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#include <cstdlib>
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#include <climits>
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#include <algorithm>
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#include <vector>
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#include <map>
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#include <set>
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#include <queue>
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#include <numeric>
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#include <sstream>
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#include <string>
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using namespace std;
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#define out(X) cerr << #X << ": " << (X) << endl
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#define SZ(X) ((int)(X.size()))
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#define LENGTH(X) ((int)(X.length()))
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#define REP(I,N) for (int I = 0; I < (N); ++I)
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#define FOR(I,L,H) for (int I = (L); I < (H); ++I)
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#define MP(X,Y) make_pair((X),(Y))
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#define PB push_back
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#define ALL(X) X.begin(), X.end()
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template <typename T> inline bool checkmin(T &a, const T &b) { return a > b ? a = b, 1 : 0; }
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template <typename T> inline bool checkmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
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typedef long long lint;
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const double EPS = 1e-9;
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int sgn(const double &x) {return (int)((x > EPS) - (x < -EPS));}
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int T,N;
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double tot,p;
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vector<double> bef,aft,init;
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int check(const double &mid) {
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bef.clear();
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aft.clear();
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for(int i = 0 ; i < N ; i++) {
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bef.push_back(init[i]);
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}
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if (sgn(mid) != 0) bef.push_back(mid);
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while(SZ(bef) > 1) {
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sort(ALL(bef));
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aft.clear();
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aft.push_back((bef[0] + bef[1]) / (1 - p));
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for(int i = 2 ; i < SZ(bef) ; i++) {
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aft.push_back(bef[i]);
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}
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bef = aft;
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}
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if (sgn(bef[0] - tot) > 0) {
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return -1;
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}
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return 1;
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}
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int main() {
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scanf("%d",&T);
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while(scanf("%lf%lf%d",&tot,&p,&N) == 3) {
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p /= 100.0;
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init.clear();
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for(int i = 0 ; i < N ; i++) {
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double w;
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scanf("%lf",&w);
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init.push_back(w);
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}
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double ans = -1;
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double l = 0.0 ,r = tot,mid;
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for(int cnt = 0 ; cnt < 200 ; cnt++){
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mid = (l + r) / 2;
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if (check(mid) != -1) {
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l = mid + EPS;
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ans = mid;
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}
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else r = mid - EPS;
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}
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if (sgn(ans + 1) <= 0) {
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printf("%d\n",-1);
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continue;
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}
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printf("%.4f\n", ans);
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}
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return 0;
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}
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