https://codeiq.jp/ace/cielavenir/q548

detectmusickey.c

#include <stdio.h>
#include <string.h>

int hash(char *str);
char name_Note[12][3]={	"C","Cs","D","Ds","E","F","Fs","G","Gs","A","As","B" };

int main(){
	unsigned short key_mask[12];
	char Note[3];
	unsigned short usedNote;

	int T;
	int N;
	int i,j;
	int i_t;
	int cnt;


	//各keyのavoid noteのbitに1
	key_mask[0]= (0x1<<0) | (0x1<<2) | (0x1<<4) | (0x1<<5) | (0x1<<7) | (0x1<<9) | (0x1<<11) ;
	for(i=1;i<12;i++){
		key_mask[i]=(key_mask[i-1]<<1) | ((key_mask[i-1]&0x800)>>11);
	}
	for(i=0;i<12;i++){
		key_mask[i]=0x0FFF & ~key_mask[i]; 
	}
	

	//あとはavoid noteを使っていないか12keysで調べるだけ。。。
	scanf("%d\n",&T);
	for(i_t=0;i_t<T;i_t++){
		scanf("%d\n",&N);
		usedNote=0;
		for(i=0;i<N;i++){
			scanf("%s",Note);
			usedNote=usedNote | 0x1<<hash(Note);
		}
		cnt=0;
		for(i=0;i<12;i++){
			if(!(usedNote & key_mask[i])){
				cnt++;
				printf(cnt==1?"%s":" %s",name_Note[i]);
			}
		}
		if(!cnt)printf("invalid");
		printf("\n");
	}
	return 0;
}



int hash(char *str){
	
	if(!strcmp(str,"C"))return 0;
	if(!strcmp(str,"Cs"))return 1;
	if(!strcmp(str,"D"))return 2;
	if(!strcmp(str,"Ds"))return 3;
	if(!strcmp(str,"E"))return 4;
	if(!strcmp(str,"F"))return 5;
	if(!strcmp(str,"Fs"))return 6;
	if(!strcmp(str,"G"))return 7;
	if(!strcmp(str,"Gs"))return 8;
	if(!strcmp(str,"A"))return 9;
	if(!strcmp(str,"As"))return 10;
	if(!strcmp(str,"B"))return 11;
	
	return -1;
	
}