Triangular matrix based on C language: why OJ is it wrong? I have considered the case where the matrix is 1, and the output result is also correct

The phenomenon and background of the problem

Judge the upper triangular matrix

Problem related code , Do not paste screenshots

#include <stdio.h>int main(){ int i,j,m,a,b,ii,q,jj,ret,num; int pd[10]; int ch[10][10]; scanf("%d",&ii); for(jj=0;jj<ii;jj++) { num=1; scanf("%d",&m); for(i=0;i<m;i++) { for(j=0;j<m;j++) { scanf("%d",&ch[i][j]); } } if(m==1) { num=0; // This block is mainly used to judge that the matrix is 1 Special circumstances of , If 1, that num Namely 0, Output in later judgment no } ret=0; for(a=0;a<m;a++) { for(b=0;b<a;b++) { if(ch[a][b]!=0) ret++; } } if(ret==0&&num!=0) { pd[jj]=1; }else{ pd[jj]=0; }} int z; for(z=0;z<ii;z++) { if(pd[z]==1) { printf("YES\n"); }else{ printf("NO\n"); } } return 0;}

Results the correct , however oj I can't get through it
The results include the input matrix as 1 and 0