IDA*不解释

#include <cstdio>
int n, T, a[20], ans, limit;
void IDA(int dep){
    int tot = 0;
    for(int i = 0; i < n; ++i)
        if(a[i + 1] != a[i] + 1)
            ++tot;
    if(!tot){ if(dep < ans) ans = dep; return ; }
    if(((tot + 2) / 3 + dep) > limit) return ;
    for(int j = 1; j < n; ++j){
        for(int i = 1; i + j - 1 <= n; ++i){
            for(int k = i + 1; k + j - 1 <= n; ++k){
                int b[20];
                for(int o = 1; o <= n; ++o)
                    b[o] = a[o];
                for(int o = k; o <= k + j - 1; ++o)
                    a[o] = b[o - k + i];
                for(int o = i + j; o <= k + j - 1; ++o)
                    a[o - j] = b[o];
                IDA(dep + 1);
                for(int o = 1; o <= n; ++o)
                    a[o] = b[o];
            }
        }
    }
}
int main(){
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        for(int i = 1; i <= n; ++i)
            scanf("%d", &a[i]);
        ans = 6;
        for(limit = 1; limit <= 4 && ans == 6; ++limit)
            IDA(0);
        if(ans != 6) printf("%d\n", ans);
        else printf("5 or more\n");
    }
}