Educational Codeforces Round #15

ECR15A.cpp

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
#define ITR(i,c) for(auto i=begin(c);i!=end(c);i++)
#define FOR(i,a,n) for(int i=a;i<(int)(n);i++)
#define FORE(x,arr) for(auto &x:arr)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) begin(c),end(c)
const int DX[4]={0,1,0,-1}, DY[4]={-1,0,1,0};
const int INF = 1e9;

int main(int argc, char const *argv[]) {
    int n;
    cin>>n;
    vector<int> a(n),b(n);
    REP(i,n) {
        cin>>a[i];
    }
    int ans=0;
    int top=0;
    FOR(i,1,n) {
        if(a[i]<=a[i-1]) {
            ans=max(ans,i-top);
            top=i;
        }
    }
    ans=max(ans,n-top);
    cout<<ans<<endl;
    return 0;
}

ECR15B.cpp

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
#define ITR(i,c) for(auto i=begin(c);i!=end(c);i++)
#define FOR(i,a,n) for(int i=a;i<(int)(n);i++)
#define FORE(x,arr) for(auto &x:arr)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) begin(c),end(c)
const int DX[4]={0,1,0,-1}, DY[4]={-1,0,1,0};
const int INF = 1e9;

int main(int argc, char const *argv[]) {
    int n;
    cin>>n;
    vector<ll> a(n);
    map<ll,ll> m;
    REP(i,n) cin>>a[i], m[a[i]]++;

    ll ans = 0;
    REP(i,n) {
        REP(k,31) {
            ans += (m[(1<<(k+1))-a[i]]);
            if(a[i]*2==(1<<(k+1))) ans--;
        }
    }
    cout<<ans/2<<endl;
    return 0;
}