失敗した。
#include <stdio.h>
#include <stdlib.h>
int main() {
int cPoints = 0;
int* pPoints = NULL;
int iPoint = 0;
scanf("%d", &cPoints);
pPoints = malloc(sizeof(int)*cPoints);
for(iPoint = 0 ; iPoint < cPoints ; iPoint++) pPoints[iPoint] = 0;
while(scanf("%d", &iPoint) != EOF) if(0 <= iPoint && iPoint < cPoints) pPoints[iPoint]++;
for(iPoint = 0 ; iPoint < cPoints ; iPoint++) if(pPoints[iPoint]%2!=0) break;
if(iPoint == cPoints) printf("グラフがオイラーグラフ\n");
else printf("グラフが非オイラーグラフ\n");
return 0;
}