Submission #1688334

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
int fa[1000100],st[1000100],a[1000100],js[1000100],tim;
bool vis[1000100];
vector <int> des[1000100];
void dfs(int s)
{
	for (int k=0;k<des[s].size();k++) if (!vis[des[s][k]]) dfs(des[s][k]);
	tim++;
	for (int k=0;k<des[s].size();k++) if (!vis[des[s][k]]) js[a[des[s][k]]]=tim;
	for (a[s]=0;;a[s]++) if (js[a[s]]!=tim) break;
}
int main()
{
	int n,top=0;scanf("%d",&n);
	for (int i=1;i<=n;i++) {scanf("%d",&fa[i]);des[fa[i]].push_back(i);}
	int now=1;while (!vis[now]) {st[++top]=now;vis[now]=true;now=fa[now];}
	int p=1;while (st[p]!=now) p++;st[top+1]=st[p];
	if ((top-p)&1) {printf("POSSIBLE\n");return 0;}
	memset(vis,0,sizeof(vis));
	for (int i=p;i<=top;i++) vis[st[i]]=true;
	for (int i=p;i<=top;i++) dfs(st[i]);
	for (int i=p;i<=top;i++) if (a[st[i]]!=a[st[i+1]]) {printf("POSSIBLE\n");return 0;}
	printf("IMPOSSIBLE\n");
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:15:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  int n,top=0;scanf("%d",&n);
                            ^
./Main.cpp:16:44: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  for (int i=1;i<=n;i++) {scanf("%d",&fa[i]);des[fa[i]].push_back(i);}
                                            ^

Judge Result