Submission #221438

#	Time	Username	Problem	Language	Result	Execution time	Memory
221438		anonymous	Fish (IOI08_fish)	C++14	80 / 100	615 ms	52188 KiB

fish

#include<iostream>
#include<algorithm>
#include<utility>
#include<vector>
#define MAXN 500005
#define fi first
#define se second
using namespace std;
int F, K, M, B[MAXN], Pos[MAXN], Ans;
bool done[MAXN];
pair<int,int> Fish[MAXN];
vector<int> S[MAXN];
vector<pair<int,int> > Ord;

class Segtree {
    int ST[MAXN*2];
public:
    void init() {
        for (int i=1; i<=2*K; i++) {
            ST[i] = 1;
        }
    }
    void upd(int p) {
        p+=K;
        for (ST[p] = (ST[p] + 1) % M; p > 1; p>>=1) {
            ST[p>>1] = (ST[p] * ST[p^1]) % M;
        }
    }
    int ask(int l, int r) {  // product on interval [l, r]
        int res = 1;
        r+=1;
        for (l += K, r += K; l < r; l >>= 1, r >>= 1) {
            if (l&1) res = (res * ST[l++])%M;
            if (r&1) res = (res * ST[--r])%M;
        }
        return res;
    }
} ST;

int FindRange(int t) {
    int thresh = S[t][ST.ask(Pos[t], Pos[t])-1], lo = 0, hi = K;
    while (lo + 1 != hi) {
        int mid = (lo + hi) >> 1;
        if (2*thresh <= Ord[mid].first) {hi = mid;}
        else {lo = mid;}
    }
    return(lo+1); //returns index
}

int main() {
    //freopen("fishin.txt","r",stdin);
    scanf("%d\n%d\n%d",&F,&K,&M);
    for (int i=1; i<=F; i++) {
        scanf("%d %d",&Fish[i].fi, &Fish[i].se);
    }
    sort(Fish+1, Fish+F+1);
    ST.init(), Pos[K+1] = K+1;
    for (int i=1; i<=F; i++) {
        B[Fish[i].se] = Fish[i].fi;
        S[Fish[i].se].push_back(Fish[i].fi);
    }

    for (int i=1; i<=K; i++) {
        Ord.push_back({B[i], i});
    }
    sort(Ord.begin(), Ord.end());
    for (int i=0; i<K; i++) {
        Pos[Ord[i].second] = i + 1;
    }
    int pt = 1;
    for (int i=1; i<=F; i++) {
        while (pt <= F && Fish[pt].fi*2 <= Fish[i].fi) {
            ST.upd(Pos[Fish[pt].se]);
            pt++;
        }
        if (!done[Fish[i].se] && Fish[i].fi == B[Fish[i].se]) {
            done[Fish[i].se] = true;
            int NonMax = ((ST.ask(Pos[Fish[i].se], Pos[Fish[i].se]) - 1) *  ST.ask(1, Pos[Fish[i].se]-1)) % M;
            int Max = (ST.ask(1, Pos[Fish[i].se]-1) * ST.ask(Pos[Fish[i].se]+1, FindRange(Fish[i].se)))%M;
            Ans = (Ans + Max + NonMax) %M;
        }
    }

    printf("%d", Ans);
}

Compilation message (stderr)

fish.cpp: In function 'int main()':
fish.cpp:52:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d\n%d\n%d",&F,&K,&M);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
fish.cpp:54:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d",&Fish[i].fi, &Fish[i].se);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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