OI-codes/S2OJ/1971/data/std.cpp

#include <stdlib.h>
#include <algorithm>
#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

typedef long double ld;

int n, m;
ld p;

ld a[1010][1010];

bool check(ld k) {
    memset(a, 0, sizeof a);
    for (int i = 0; i < n; i++) {
        a[i][m] = k;
    }
    for (int i = n - 1; i >= 0; i--) {
        for (int j = m - 1; j >= 0; j--) {
            a[i][j] = p * a[i + 1][j] + (1 - p) * a[i][j + 1] + 1;
            if (i | j) {
                if (a[i][j] > k) {
                    a[i][j] = k;
                }
            }
        }
    }
    return a[0][0] < k;
}

int main() {
    cin >> m >> n >> p;
    p /= 100;
    ld l = 0, r = 1000000010;
    for (int i = 0; i < 100; i++) {
        ld mid = (l + r) / 2;
        if (check(mid)) {
            r = mid;
        } else {
            l = mid;
        }
    }
    cout.setf(ios::showpoint | ios::fixed);
    cout.precision(20);
    cout << min((l + r) / 2, 1e9l) << endl;
}