代码略长

#include<stdio.h>

int a[5001];

int main(){
    int n;
    scanf("%d",&n);
    int t=n/2+1,s=1,t2;
    while(t--){
        for(int i=1;i<=t;++i)printf("  ");
        for(int i=1;i<=s;++i)printf("* ");
        printf("\n");
        s+=2;
    }
    s=n-2,t2=1;
    while(t2<=n/2){
        for(int i=1;i<=t2;++i)printf("  ");
        for(int i=1;i<=s;++i)printf("* ");
        printf("\n");
        s-=2;
        t2++;
    }
    return 0;
}