Submission #66080

#	Time	Username	Problem	Language	Result	Execution time	Memory
66080		ikura355	007 (CEOI14_007)	C++14	100 / 100	534 ms	18820 KiB

007

#include<bits/stdc++.h>
using namespace std;

const int maxn = 2e5 + 5;
const int inf = 1e9;

int n,m,a,b,s1,s2;
vector<int> way[maxn];
int d[2][maxn];
int q[maxn];
int p[maxn], wow[maxn];

int sssp(int k, int u) {
    int l = 1, r = 0;
	for(int i=1;i<=n;i++) d[k][i] = inf;
	d[k][u] = 0; q[++r] = u;
	while(l<=r) {
		int u = q[l++];
		for(auto v : way[u]) {
			if(d[k][v] > d[k][u] + 1) {
				d[k][v] = d[k][u] + 1; q[++r] = v;
			}
		}
	}
}

bool cmp(int x, int y) {
    if(d[0][x]!=d[0][y]) return d[0][x] < d[0][y];
    if(d[1][x]!=d[1][y]) return d[1][x] < d[1][y];
    return x<y;
}

int main() {
	scanf("%d%d",&n,&m);
	scanf("%d%d%d%d",&a,&b,&s1,&s2);
	for(int i=1;i<=m;i++) {
		int u,v; scanf("%d%d",&u,&v);
		way[u].push_back(v); way[v].push_back(u);
	}
	sssp(0,s1); sssp(1,s2);
	if(d[0][a]>d[0][b] || d[1][a]>d[1][b]) return !printf("-1");
    int res = min(d[0][b]-d[0][a], d[1][b]-d[1][a]);
//    printf("res = %d\n",res);
    if(d[0][a] == d[1][a] && d[0][b] == d[1][b]) {
        for(int i=1;i<=n;i++) p[i] = i;
        sort(&p[1],&p[n+1],cmp);
        for(int i=1;i<=n;i++) {
            int u = p[i];
            for(auto v : way[u]) {
                if(d[0][v]==d[0][u]+1 && d[1][v]==d[1][u]+1) wow[v] = max(wow[v], wow[u]+1);
            }
//            printf("wow %d = %d\n",u,wow[u]);
        }
        if(wow[a]+res<wow[b]) res = res-1;
    }
    printf("%d",max(0,res));
}

Compilation message (stderr)

007.cpp: In function 'int sssp(int, int)':
007.cpp:25:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
007.cpp: In function 'int main()':
007.cpp:34:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
007.cpp:35:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d",&a,&b,&s1,&s2);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
007.cpp:37:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int u,v; scanf("%d%d",&u,&v);
            ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70