Submission #3786048

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Source Code Expand

#include<cstdio>
#include<algorithm>

class Solution{
private :
	static const int maxn = 5e5 + 7;
	static const int maxm = 5e5;
	static const int mod = 998244353;
	
	int n, m, frac[maxn * 2], invf[maxn * 2], ans, tot, sum;
	
	void Init(int x) {
		frac[0] = 1;
		for (register int i = 1; i <= x; i++) {
			frac[i] = 1ll * frac[i - 1] * i % mod;
		}
		invf[x] = Kasumi(frac[x], mod - 2);
		for (register int i = x - 1; i >= 0; i--) {
			invf[i] = 1ll * invf[i + 1] * (i + 1) % mod;
		}
	}
	
	int Kasumi(int a, int b) {
		int res = 1, base = a;
		for (; b; b >>= 1) {
			if (b & 1) {
				res = 1ll * res * base % mod;
			}
			base = 1ll * base * base % mod;
		}
		return res;
	}
	
	int Inv(int x) {
		return Kasumi(x, mod - 2);
	}
	
	int A(int n, int m) {
		if (n == m || !m) {
			return frac[n];
		}
		return 1ll * frac[n] * invf[m] % mod;
	}
	
	int C(int n, int m) {
		if (n == m || !m) {
			return 1;
		}
		return 1ll * A(n, m) * invf[n - m] % mod;
	}
	
public :
	Solution() {
		Get();
		Solve();
	}
	
	void Get() {
		scanf("%d %d", &n, &m);
	}
	
	void Solve() {
        Init(n + m);
        if (n > m) {
            std :: swap(n, m);
        }
        for (register int i = 1; i <= n; i++) {
            tot += 1ll * C(2 * i, i) * C(n - i + m - i, n - i) % mod;
            if (tot >= mod) {
                tot -= mod;
            }
        }
        sum = C(n + m, n);
        printf("%lld\n", (1ll * tot * Inv(sum) % mod * Inv(2) + m) % mod);
	}
};
Solution sol;

int main() {}

Submission Info

Compile Error

./Main.cpp: In member function ‘void Solution::Get()’:
./Main.cpp:59:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &n, &m);
                         ^

Judge Result