提出 #64057664

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ソースコード 拡げる

#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}

std::vector<std::vector<int> > hen;

std::vector<int> depth;
void dfs(int i, int prev) {
	for (auto j : hen[i]) if (j != prev) {
		depth[j] = depth[i] + 1;
		dfs(j, i);
	}
}

int main() {
	int n = ri();
	hen.resize(n);
	
	for (int i = 1; i < n; i++) {
		int x = ri() - 1;
		int y = ri() - 1;
		hen[x].push_back(y);
		hen[y].push_back(x);
	}
	
	depth.resize(n);
	dfs(0, -1);
	
	
	std::set<std::pair<int, int> > remaining;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < i; j++) if ((depth[i] + depth[j]) % 2) remaining.insert({j, i});
	}
	for (int i = 0; i < n; i++) {
		for (auto j : hen[i]) remaining.erase({i, j}), remaining.erase({j, i});
	}
	
	if (remaining.size() % 2) puts("First");
	else puts("Second");
	fflush(stdout);
	
	while (1) {
		if (remaining.size() % 2) {
			assert(remaining.size());
			printf("%d %d\n", remaining.begin()->first + 1, remaining.begin()->second + 1);
			fflush(stdout);
			remaining.erase(remaining.begin());
		} else {
			int x = ri() - 1;
			int y = ri() - 1;
			if (x == -2) break;
			assert(remaining.count({x, y}) || remaining.count({y, x}));
			remaining.erase({x, y});
			remaining.erase({y, x});
		}
	}
	
	
	
	return 0;
}

提出情報

コンパイルエラー

Main.cpp: In function ‘int ri()’:
Main.cpp:5:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
    5 |         scanf("%d", &n);
      |         ~~~~~^~~~~~~~~~

ジャッジ結果