【Codeforces Round #398 (Div. 2)】Codeforces 767A Snacktower

According to an old legeng, a long time ago Ankh-Morpork residents did
something wrong to miss Fortune, and she cursed them. She said that at
some time n snacks of distinct sizes will fall on the city, and the
residents should build a Snacktower of them by placing snacks one on
another. Of course, big snacks should be at the bottom of the tower,
while small snacks should be at the top. Years passed, and once
different snacks started to fall onto the city, and the residents
began to build the Snacktower. However, they faced some troubles.
Each day exactly one snack fell onto the city, but their order was
strange. So, at some days the residents weren’t able to put the new
stack on the top of the Snacktower: they had to wait until all the
bigger snacks fell. Of course, in order to not to anger miss Fortune
again, the residents placed each snack on the top of the tower
immediately as they could do it. Write a program that models the
behavior of Ankh-Morpork residents. Input The first line contains
single integer n (1 ≤ n ≤ 100 000) — the total number of snacks. The
second line contains n integers, the i-th of them equals the size of
the snack which fell on the i-th day. Sizes are distinct integers from
1 to n. Output Print n lines. On the i-th of them print the sizes of
the snacks which the residents placed on the top of the Snacktower on
the i-th day in the order they will do that. If no snack is placed on
some day, leave the corresponding line empty.

从大到小放，小的只能在最后一个大的放的那天放。

#include<cstdio>#include<vector>#include<algorithm>using namespace std;vector<int> f[100010];int a[100010],plc[100010];int main(){    int n,now=0;    scanf("%d",&n);    for (int i=1;i<=n;i++)        scanf("%d",&a[i]),plc[a[i]]=i;    for (int i=n;i;i--)    {        f[max(now,plc[i])].push_back(i);        now=max(now,plc[i]);    }    for (int i=1;i<=n;i++)    {        for (int j=0;j<f[i].size();j++)        {            if (j) putchar(' ');            printf("%d",f[i][j]);        }        putchar('\n');    }}