Submission #62940

#	Time	Username	Problem	Language	Result	Execution time	Memory
62940		updown1	Horses (IOI15_horses)	C++17	17 / 100	783 ms	44908 KiB

horses

/*
segtree. Each element i stores (X[0]*X[1]*...*X[i]*Y[i])%MOD
*/
#include "horses.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define For(i, a, b) for(int i=a; i<b; i++)
#define ffi For(i, 0, N1)
#define ffj For(j, 0, P)
#define ffa ffi ffj
//#define s <<" "<<
//#define c <<" : "<<
#define w cout
#define e endl
#define pb push_back
#define mp make_pair
#define a first
#define b second
//#define int ll
const ll MAXN = 500000, MOD = 1000000007;
int N1;
ll tree[4*MAXN+1], lazy[4*MAXN+1], xx[MAXN], yy[MAXN];

ll mI(ll x, ll y) { /// call mI(x, MOD-2)
    /// x^y
    if (y == 0) return 1;
    if (y == 1) return x;
    ll p = mI(x, y/2);
    p = (p*p)%MOD;
    if (y%2 == 1) p = (p*x)%MOD;
    return p;
}

void push(int x, int L, int R) {
    tree[x] *= lazy[x];
    tree[x] %= MOD;
    if (L != R) {
        lazy[x*2] *= lazy[x];
        lazy[x*2] %= MOD;
        lazy[x*2+1] *= lazy[x];
        lazy[x*2+1] %= MOD;
    }
    lazy[x] = 1;
}
void update(int x, int L, int R, int oL, int oR, ll v) {
    push(x, L, R);
    if (R < oL || oR < L) return;
    if (oL <= L && R <= oR) {
        lazy[x] *= v;
        lazy[x] %= MOD;
        push(x, L, R);
        return;
    }
    update(x*2, L, (L+R)/2, oL, oR, v);
    update(x*2+1,(L+R)/2+1,R,oL, oR, v);
    tree[x] = max(tree[x*2], tree[x*2+1]);
}
int answer() {
    push(1, 0, N1-1);
    assert(tree[1] > 0);
    return tree[1];
}

int init(int N, int X[], int Y[]) {
    N1 = N;
    For (i, 0, 4*MAXN+1) tree[i] = lazy[i] = 1;
    ffi xx[i] = X[i], yy[i] = Y[i];
    ffi update(1, 0, N-1, i, N-1, X[i]), update(1, 0, N-1, i, i, Y[i]);
    return answer();
}
int updateX(int pos, int val) {
    //w<< pos << " " << val << " " << (mI(xx[pos], MOD-2)*xx[pos])%MOD<<e;
    update(1, 0, N1-1, pos, N1-1, mI(xx[pos], MOD-2));
    update(1, 0, N1-1, pos, N1-1, val);
    xx[pos] = val;
	return answer();
}
int updateY(int pos, int val) {
    update(1, 0, N1-1, pos, pos, mI(yy[pos], MOD-2));
    update(1, 0, N1-1, pos, pos, val);
    yy[pos] = val;
	return answer();
}

Compilation message (stderr)

horses.cpp: In function 'int answer()':
horses.cpp:62:18: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
     return tree[1];
            ~~~~~~^

• Subtask 1: 17 / 17
• Subtask 2: 0 / 17
• Subtask 3: 0 / 20
• Subtask 4: 0 / 23
• Subtask 5: 0 / 23