最近忙。。。先上代碼吧。。。有空繼續寫題解。。。

#include<cstdio>
#include<queue>
using namespace std;
#define MAXN 3005

int n, ans, t, s;
int nn;
int a[MAXN * 2];

int main(){
    scanf( "%d", &n );
    for ( int i = 1; i <= n; ++i ) scanf( "%d", &t ), a[t]++, s += t, nn = max( nn, t );
    t 
 
= 0;
    for ( int i = 1; i <= 6000; ++i ){
        if ( t == 0 && i > nn ) break;
        if ( t > 0 && a[i] == 0 ) t--, ans += i;
        if ( a[i] > 1 ) t += a[i] - 1;
        if ( a[i] ) ans += i;
    }
    printf( "%d\n", ans - s );
    return 0;
}

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