competitive-programing

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:heavy_check_mark: verify/Datastructure_lazyseg_bina.test.cpp

Depends on

Code

#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=4021"
#include "../Utility/template.hpp"
#include "../Datastructure/lazysegtree.hpp"


struct S{
	ll idx;
	ll x;
};
S op(S a,S b){
    if(a.x==b.x){
        if(a.idx>b.idx) return a;
        return b;
    }
	if(a.x>b.x) return a;
	return b;
}
S e(){
	return {-1,(ll)(-1e18)};
}
using F = ll;
S mapping(F f,S a){
    a.x+=f;
    return a;
}
F comb(F f,F g){
    return f+g;
}
F id(){
    return 0;
}

using segtree = lazysegtree<S,op,e,F,mapping,comb,id>;

int main(){
	int h,w;
	cin>>h>>w;
	vector<string> s(h);
	rep(i,0, h) cin>>s.at(i);
	vector<vector<ll>> dp(h+1,vector<ll>(w+1,0));
	{
		vector<vector<ll>> dp1(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp2(h+1,vector<ll>(w+1,0));
		for(int i=h-1;i>=0;i--){
			for(int j=w-1;j>=0;j--){
				if(s.at(i).at(j)=='0') continue;
				dp1.at(i).at(j)=dp1.at(i+1).at(j)+1;
				dp2.at(i).at(j)=dp2.at(i).at(j+1)+1;
				dp.at(i).at(j)=min(dp1.at(i).at(j),dp2.at(i).at(j));
			}
		}
	}
	vector<string> rs(h);
	rep(i,0, h) rep(j,0, w){
		rs.at(i)+=s.at(h-1-i).at(w-1-j);
	}
	vector<vector<ll>> rdp(h+1,vector<ll>(w+1,0));
	{
		vector<vector<ll>> rrdp(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp1(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp2(h+1,vector<ll>(w+1,0));
		for(int i=h-1;i>=0;i--){
			for(int j=w-1;j>=0;j--){
				if(rs.at(i).at(j)=='0') continue;
				dp1.at(i).at(j)=dp1.at(i+1).at(j)+1;
				dp2.at(i).at(j)=dp2.at(i).at(j+1)+1;
				rrdp.at(i).at(j)=min(dp1.at(i).at(j),dp2.at(i).at(j));
			}
		}
		rep(i,0, h) rep(j,0, w){
			rdp.at(i).at(j)=rrdp.at(h-1-i).at(w-1-j);
		}
	}
    ll ans=0;
	for(int k=-h+1;k<w;k++){
		vector<S> tmp;
        int d=0;
		for(int i=0;i<h;i++){
			int j=i+k;
			if(j<0||j>=w) continue;
			tmp.push_back({d,rdp.at(i).at(j)-d});
            d++;
		}
        segtree seg(tmp);
        d=0;
		for(int i=0;i<h;i++){
			int j=i+k;
			if(j<0||j>=w) continue;
            //if(dp.at(i).at(j)==0) continue;
			auto ch = [&](S now) {
				return now.x < 0;
			};
            ll v =seg.min_left(dp.at(i).at(j)+d,ch);
			//cout << dp.at(i).at(j) << endl;
            if(v > 0){
				v--;
                ans=max(ans,v-d+1);
            }
            d++;
            seg.apply(0,tmp.size(),1);
		}
	}
    cout<<ans<<endl;
}
#line 1 "verify/Datastructure_lazyseg_bina.test.cpp"

#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=4021"
#line 1 "Utility/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define rrep(i, s, t) for (ll i = (ll)(t) - 1; i >= (ll)(s); i--)
#define all(x) begin(x), end(x)

#define TT template <typename T>
TT using vec = vector<T>;
template <class T1, class T2> bool chmin(T1 &x, T2 y) {
    return x > y ? (x = y, true) : false;
}
template <class T1, class T2> bool chmax(T1 &x, T2 y) {
    return x < y ? (x = y, true) : false;
}
struct io_setup {
    io_setup() {
        ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
        cout << fixed << setprecision(15);
    }
} io_setup;

/*
@brief verify用テンプレート
*/
#line 1 "Datastructure/lazysegtree.hpp"
template <class S,
          S (*op)(S, S),
          S (*e)(),
          class F,
          S (*mp)(F, S),
          F (*cm)(F, F),
          F (*id)()>
struct lazysegtree {
    int n;
    int sz;
    int log;
    vec<S> d;
    vec<F> lz;
    lazysegtree(int n) : lazysegtree(vec<S>(n, e())) {}
    lazysegtree(const vec<S> &v) : n((int)(v.size())) {
        log = 1;
        while ((1 << log) < n) log++;
        sz = 1 << log;
        d.resize(2 * sz, e());
        lz.resize(2 * sz, id());
        rep(i, 0, n) d[sz + i] = v[i];
        rrep(i, 1, sz) update(i);
    }

    void update(int i) { d[i] = op(d[i << 1], d[i << 1 | 1]); }

    void all_apply(int i, F f) {
        d[i] = mp(f, d[i]);
        if (i < sz) lz[i] = cm(f, lz[i]);
    }

    void push(int k) {
        all_apply(k * 2, lz[k]);
        all_apply(k * 2 + 1, lz[k]);
        lz[k] = id();
    }

    S prod(int l, int r) {
        assert(0 <= l && l <= r && r <= n);
        if (l == r) return e();

        l += sz;
        r += sz;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push((r - 1) >> i);
        }

        S sml = e(), smr = e();
        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }

        return op(sml, smr);
    }

    void apply(int l, int r, F f) {
        assert(0 <= l && l <= r && r <= n);
        if (l == r) return;

        l += sz;
        r += sz;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push((r - 1) >> i);
        }

        {
            int l2 = l, r2 = r;
            while (l < r) {
                if (l & 1) all_apply(l++, f);
                if (r & 1) all_apply(--r, f);
                l >>= 1;
                r >>= 1;
            }
            l = l2;
            r = r2;
        }

        for (int i = 1; i <= log; i++) {
            if (((l >> i) << i) != l) update(l >> i);
            if (((r >> i) << i) != r) update((r - 1) >> i);
        }
    }

    // 以下、必要になったら書く（全て独立)

    template <class G> int max_right(int l, G g) {
        assert(0 <= l && l <= n);
        assert(g(e()));
        if (l == n) return n;
        l += sz;
        for (int i = log; i >= 1; i--) push(l >> i);
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!g(op(sm, d[l]))) {
                while (l < sz) {
                    push(l);
                    l = (2 * l);
                    if (g(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - sz;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return n;
    }

    template <class G> int min_left(int r, G g) {
        assert(0 <= r && r <= n);
        assert(g(e()));
        if (r == 0) return 0;
        r += sz;
        for (int i = log; i >= 1; i--) push((r - 1) >> i);
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!g(op(d[r], sm))) {
                while (r < sz) {
                    push(r);
                    r = (2 * r + 1);
                    if (g(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - sz;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

    void set(int p, S x) {
        assert(0 <= p && p < n);
        p += sz;
        rrep(i, 1, log + 1) push(p >> i);
        d[p] = x;
        rep(i, 1, log + 1) update(p >> i);
    }

    S all_prod() { return d[1]; }

    S get(int p) {
        assert(0 <= p && p < n);
        p += sz;
        for (int i = log; i >= 1; i--) push(p >> i);
        return d[p];
    }

    void apply(int p, F f) {
        assert(0 <= p && p < n);
        p += sz;
        for (int i = log; i >= 1; i--) push(p >> i);
        d[p] = mapping(f, d[p]);
        for (int i = 1; i <= log; i++) update(p >> i);
    }
};

/*
@brief lazysegtree
@docs doc/lazysegtree.md
*/
#line 5 "verify/Datastructure_lazyseg_bina.test.cpp"


struct S{
	ll idx;
	ll x;
};
S op(S a,S b){
    if(a.x==b.x){
        if(a.idx>b.idx) return a;
        return b;
    }
	if(a.x>b.x) return a;
	return b;
}
S e(){
	return {-1,(ll)(-1e18)};
}
using F = ll;
S mapping(F f,S a){
    a.x+=f;
    return a;
}
F comb(F f,F g){
    return f+g;
}
F id(){
    return 0;
}

using segtree = lazysegtree<S,op,e,F,mapping,comb,id>;

int main(){
	int h,w;
	cin>>h>>w;
	vector<string> s(h);
	rep(i,0, h) cin>>s.at(i);
	vector<vector<ll>> dp(h+1,vector<ll>(w+1,0));
	{
		vector<vector<ll>> dp1(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp2(h+1,vector<ll>(w+1,0));
		for(int i=h-1;i>=0;i--){
			for(int j=w-1;j>=0;j--){
				if(s.at(i).at(j)=='0') continue;
				dp1.at(i).at(j)=dp1.at(i+1).at(j)+1;
				dp2.at(i).at(j)=dp2.at(i).at(j+1)+1;
				dp.at(i).at(j)=min(dp1.at(i).at(j),dp2.at(i).at(j));
			}
		}
	}
	vector<string> rs(h);
	rep(i,0, h) rep(j,0, w){
		rs.at(i)+=s.at(h-1-i).at(w-1-j);
	}
	vector<vector<ll>> rdp(h+1,vector<ll>(w+1,0));
	{
		vector<vector<ll>> rrdp(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp1(h+1,vector<ll>(w+1,0));
		vector<vector<ll>> dp2(h+1,vector<ll>(w+1,0));
		for(int i=h-1;i>=0;i--){
			for(int j=w-1;j>=0;j--){
				if(rs.at(i).at(j)=='0') continue;
				dp1.at(i).at(j)=dp1.at(i+1).at(j)+1;
				dp2.at(i).at(j)=dp2.at(i).at(j+1)+1;
				rrdp.at(i).at(j)=min(dp1.at(i).at(j),dp2.at(i).at(j));
			}
		}
		rep(i,0, h) rep(j,0, w){
			rdp.at(i).at(j)=rrdp.at(h-1-i).at(w-1-j);
		}
	}
    ll ans=0;
	for(int k=-h+1;k<w;k++){
		vector<S> tmp;
        int d=0;
		for(int i=0;i<h;i++){
			int j=i+k;
			if(j<0||j>=w) continue;
			tmp.push_back({d,rdp.at(i).at(j)-d});
            d++;
		}
        segtree seg(tmp);
        d=0;
		for(int i=0;i<h;i++){
			int j=i+k;
			if(j<0||j>=w) continue;
            //if(dp.at(i).at(j)==0) continue;
			auto ch = [&](S now) {
				return now.x < 0;
			};
            ll v =seg.min_left(dp.at(i).at(j)+d,ch);
			//cout << dp.at(i).at(j) << endl;
            if(v > 0){
				v--;
                ans=max(ans,v-d+1);
            }
            d++;
            seg.apply(0,tmp.size(),1);
		}
	}
    cout<<ans<<endl;
}
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