UVA 10341- Solve It

10341.cpp

/**
 *  Author  : Pnictogen
 *  Task    :
 *  Algo    :
**/
#include <bits/stdc++.h>

#define endl          '\n'
#define sqr(x)        (x) * (x)
#define gcd(x,y)      __gcd(x,y)
#define lcm(x,y)      ((x/gcd(x,y)) * y)
#define sz(x)         (int)x.size()
#define all(x)        (x).begin(),(x).end()
#define rall(x)       (x).rbegin(),(x).rend()
#define prec(x)       fixed<<setprecision(x)
#define min3(a,b,c)   min(a,min(b,c))
#define max3(a,b,c)   max(a,max(b,c))
#define min4(a,b,c,d) min(a,min(b,min(c,d)))
#define max4(a,b,c,d) max(a,max(b,max(c,d)))
#define unsyncIO      ios_base::sync_with_stdio(false); cin.tie(nullptr)

using namespace std;
using ll = long long;
using db = double;
using ld = long double;
using ull = unsigned long long;

const ld PI = acos((ld) - 1);
const int MOD = 1e9 + 7;
const ll INF = 2e18 + 1;
const ld EPS = 1e-9;
const int MX = 2e5;

#ifdef LOCAL
#include"debug.h"
#else
#define debug(...)
#endif

ld p, q, r, s, t, u;
ld method(ld x) {
	return (p * (1 / exp(x))) + q * sin(x) + r * cos(x) + s * tan(x) + (t * pow(x, 2)) + u;
}

void solve() {
	while (cin >> p >> q >> r >> s >> t >> u) {
		if (method(1) * method(0) > 0) { // this condition is based by bisection method(if you don't know it, search for it)
			cout << "No solution" << endl;
		} else { // find root(x) using binary search
			ld low = 0.0, high = 1.0, x, ans;
			cout << fixed << setprecision(4);
      
			while (low < high) {
				x = (low + high) / 2.0;
				ans = method(x);
				if (ans < 0) high = x - EPS; // for non increasing funtion
				else  low = x + EPS; // for decreasing function
			}

			cout << x << endl;
		}
	}
}

int main() {

#ifdef LOCAL
	clock_t tStart = clock();
	freopen("in.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
#endif
	unsyncIO;

	int T = 1;	//cin >> t;

	while (T--) {
		solve();
	}

#ifdef LOCAL
	cerr << "\nRuntime: " << (ld) (clock() - tStart) / CLOCKS_PER_SEC << " Seconds" << endl;
#endif
	return 0;
}