HDU

最右策略就是从前面找最大的往后移

就看大的在前面的个数，相当于一个指针从后往前找，同时记录位置和当前位置应该出现的值

#include <iostream>#include <cstdio>#include <cstring>#include <cstdlib>#include <cmath>#include <set>#include <queue>#include <algorithm>#include <vector>#include <cctype>#include <stack>#include <sstream>#include <list>#include <map>#include <assert.h>#define debug() puts("************")#define MS(a,b) memset(a,b,sizeof a)using namespace std;typedef long long ll;const int maxn = 1000000+7;int T, n;ll a[maxn], b[maxn];int main(){    ios::sync_with_stdio(0);        int T;    cin>>T;    int kase = 1;    while(T--)    {        int n;        cin>>n;        for (int i = 0; i < n; ++i) {            cin >> a[i];        }        int ans = 0, t = n, id = n-1;        while(1) {            if(a[id] == t) { id--; t--; }            else if(t > a[id]) { ans++; t--; }            else if(t < a[id]) { id--; }            if(id < 0 || t == 1) break;        }        cout << "Case #" << kase++ << ": " << (ans) << endl ;    }}