Language: C

t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
		}
		puts(z?"":"0");
	}
	return 0;
}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      | ^~
main.c:1:1: error: type defaults to 'int' in declaration of 't1' [-Wimplicit-int]
main.c:1:8: error: type defaults to 'int' in declaration of 't2' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |        ^~
main.c:1:15: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |               ^
main.c:1:17: error: type defaults to 'int' in declaration of 'j' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                 ^
main.c:1:19: error: type defaults to 'int' in declaration of 'k' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                   ^
main.c:1:21: error: type defaults to 'int' in declaration of 'z' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                     ^
main.c:1:23: error: type defaults to 'int' in declaration of 'c' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                       ^
main.c:1:25: error: type defaults to 'int' in declaration of 'r' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                         ^
main.c:1:27: error: return type defaults to 'int' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                           ^
main.c: In function 'f':
main.c:1:27: error: type of 'x' defaults to 'int' [-Wimplicit-int]
main.c:1:40: error: implicit declaration of function 'memcpy' [-Wimplicit-function-declaration]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                        ^~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'memcpy'
  +++ |+#include <string.h>
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
main.c:1:40: warning: incompatible implicit declaration of built-in function 'memcpy' [-Wbuiltin-declaration-mismatch]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                        ^~~~~~
main.c:1:40: note: include '<string.h>' or provide a declaration of 'memcpy'
main.c: At top level:
main.c:1:174: error: return type defaults to 'int' [-Wimplicit-int]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                                                                                                                                                              ^~~~
main.c: In function 'main':
main.c:1:198: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                                                                                                                                                                                      ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
main.c:1:198: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                                                                                                                                                                                      ^~~~~
main.c:1:198: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:215: error: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
    1 | t1[12],t2[12],i,j,k,z,c,r;f(x){r=0;c=4;memcpy(t2,t1,48);t2[x]-=2;for(k=1;k<=9;){t2[k]--?t2[k]>1?t2[k]-=2,r=!--c:t2[k+1]&&t2[k+2]?--t2[k+1],--t2[k+2],r=!--c:0:0;t2[k]||++k;}}main(){char s[16];for(;~scanf(" %s",s);){memset(t1,0,48);for(z=i=0;i<13;)++t1[s[i++]-'0'];for(i=1;i<=9;i++){if(t1[i]<4){++t1[i];for(r=0,j=1;j<=9&&!r;j++,r=0){if(t1[j]>1&&(f(j),r)){z++&&putchar(32);print("%d",i);}}--t1[i];}
      |                                                                                                                                                                                                                       ^~~~~~
main.c:1:215: note: include '<string.h>' or provide a declaration of 'memset'
main.c:1:215: warning: incompatible implicit declaration of built-in function 'memset' [-Wbuiltin-declaration-mismatch]
main.c:1:215: note: include '<string.h>' or provide a declaration of 'memset'
main.c:1:359: error: implicit