Submission #1869952

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Source Code Expand

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
typedef long long ll ;
#define rep(i, a, b) for (int i = a; i <= b; ++ i) 
const int N = 1e5 + 5, M = N << 1, inf = 1e9 + 7 ;
using namespace std ;

int n, e, ter[M], nxt[M], lnk[N], w[M], sz[N], fa[N] ;
ll ans ;

void add(int x, int y, int z) {
	ter[++ e] = y, nxt[e] = lnk[x], lnk[x] = e, w[e] = z ;
}

void dfs(int p, int las) {
	sz[p] = 1, fa[p] = las ;
	for (int i = lnk[p] ; i; i = nxt[i]) if (ter[i] != las) {
		dfs(ter[i], p) ;
		sz[p] += sz[ter[i]] ;
		ans += 2LL * w[i] * min(sz[ter[i]], n - sz[ter[i]]) ;
	}
}

int main() {
	scanf("%d", &n) ;
	int x, y, z ;
	rep(i, 1, n - 1) {
		scanf("%d%d%d", &x, &y, &z) ;
		add(x, y, z), add(y, x, z) ;
	}	
	ans = 0 ;
	dfs(1, 0) ;
	rep(i, 1, n) for (int j = lnk[i] ; j; j = nxt[j]) if (ter[j] != fa[i]) {
		if (sz[ter[j]] == n / 2 && n - sz[ter[j]] == n / 2) {
			printf("%lld\n", ans - w[j]) ;
			return 0 ; 
		}
	}
	rep(i, 1, n) {
		bool flg = true ; int mn = inf ;
		for (int j = lnk[i] ; j; j = nxt[j]) {
			if (ter[j] == fa[i]) flg &= (n - sz[i] <= n / 2) ;
				else flg &= (sz[ter[j]] <= n / 2) ;
			mn = min(mn, w[j]) ;
		}
		if (flg) {
			printf("%lld\n", ans - mn) ;
			return 0 ;
		}
	}
	return 0 ; 
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:28:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n) ;
                  ^
./Main.cpp:31:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d", &x, &y, &z) ;
                               ^

Judge Result