Submission #3230599

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Source Code Expand

#include <bits/stdc++.h>

using namespace std ;

#define N 500010
#define inf 0x3f3f3f3f

int head[ N ] , cnt ;
int d[ N ] , vis[ N ] , q[ N ] ;
int n , m ;
struct node {
	int to , nxt , v ;
}e[ N ] ; 

void ins( int u , int v , int w ) {
	e[ ++ cnt ].to = v ;
	e[ cnt ].nxt = head[ u ] ;
	e[ cnt ].v = w ;
	head[ u ] = cnt ;
} 

map<pair<int,int>,int>mp;

int tot = 0 ;

int get_num( int x , int y ) {
	if( !mp.count( make_pair( x , y ) ) ) mp[ make_pair( x , y ) ] = ++tot ;
	return mp[ make_pair( x , y ) ] ;
}

void spfa() {
	for( int i = 1 ; i <= tot ; i ++ ) d[ i ] = inf ;
	vis[ 1 ] = q[ 1 ] = 1 ;
	d[ 1 ] = 0 ;
	int l = 1 , r = 2 ;
	while( l < r ) {
		int u = q[ l ++ ] ;
		vis[ u ] = 0 ;
		for( int i = head[ u ] ; i ; i = e[ i ].nxt ) {
			int v = e[ i ].to ;
			if( d[ v ] > d[ u ] + e[ i ].v ) {
				d[ v ] = d[ u ] + e[ i ].v ;
				if( !vis[ v ] ) vis[ v ] = 1 , q[ r ++ ] = v ;
			}
		}
	}
	if( d[ n ] == inf ) puts( "-1" ) ;
	else printf( "%d\n" , d[ n ] / 2 ) ;
}

int main() {
	scanf( "%d%d" , &n , &m ) ;
	tot = n ;
	for( int i = 1 ; i <= m ; i ++ ) {
		int x , y , c ;
		scanf( "%d%d%d" , &x , &y , &c ) ;
		int n1 = get_num( x , c ) , n2 = get_num( y , c ) ;
		ins( x , n1 , 1 ) ;
		ins( n1 , x , 1 ) ;
		ins( n1 , y , 1 ) ;
		ins( y , n1 , 1 ) ;
		ins( n1 , n2 , 0 ) ;
		ins( n2 , n1 , 0 ) ;
	}
	spfa() ;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:52:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf( "%d%d" , &n , &m ) ;
                            ^
./Main.cpp:56:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf( "%d%d%d" , &x , &y , &c ) ;
                                    ^

Judge Result