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Submission #515947

# Submission time Handle Problem Language Result Execution time Memory
515947 2022-01-20T07:31:25 Z wfe2017 Distributing Candies (IOI21_candies) C++17
100 / 100
 280 ms 41584 KB 
#include <bits/stdc++.h>

// same as the nlog2 solution, except that we do binary search on the segment tree
using namespace std;

const int n_bits=19;
const long long inf = 1e18;
long long minseg[1<<(n_bits+1)];
long long maxseg[1<<(n_bits+1)];
long long lazyadd[1<<(n_bits+1)];

// a standard lazy propagation segment tree
// here we need to support both min and max
// so it is essentially 2 segtrees combined together
// but we only need 1 copy of lazy add
struct segtree {
    long long last_value = 0;
    long long small = inf;
    long long big = -inf;

    segtree() {}

    void update(int node, int change) { // treated as a suffix update
        last_value += change;
        node += (1<<n_bits);
        lazyadd[node] += change;
        while(node>1) {
            if(node%2==0) {
                lazyadd[node+1] += change;
            }
            minseg[node/2] = min(minseg[node]+lazyadd[node], minseg[node^1]+lazyadd[node^1]);
            maxseg[node/2] = max(maxseg[node]+lazyadd[node], maxseg[node^1]+lazyadd[node^1]);
            node = node/2;
        }
    }

    int solve(int capacity) { // returns the largest index i, such that the range >= c
        int node = 1;
        small = inf;
        big = -inf;
        long long lz = 0;
        while(node < (1<<n_bits)) {
            lz += lazyadd[node];
            node *= 2;
            if(max(big, maxseg[node+1]+lazyadd[node+1]+lz) - min(small, minseg[node+1]+lazyadd[node+1]+lz) > capacity) {
                node++;
            } else {
                big = max(big, maxseg[node+1]+lazyadd[node+1]+lz);
                small = min(small, minseg[node+1]+lazyadd[node+1]+lz);
            }
        }
        if(minseg[node] + lazyadd[node] + lz < last_value) {
            return capacity - (big - last_value);
        } else {
            return last_value - small;
        }
    }
};

vector<pair<int,int>> toggle[(int)6e5];
// this tells you what you need to toggle on/off as you move across the boxes
// stores a pair indicating the query id and the change in number of candies
vector<int> distribute_candies(vector<int> C, vector<int> L, vector<int> R, vector<int> V) {
    int n = C.size();
    int q = L.size();
    segtree s;

    for(int i=0; i<q; i++) {
        toggle[L[i]].push_back(make_pair(i, V[i]));
        toggle[R[i]+1].push_back(make_pair(i, -V[i]));
    }

    vector<int> ans;
    ans.resize(n);
    for(int i=0; i<n; i++) {
        for(pair<int,int> p: toggle[i]) {
            s.update(p.first+2, p.second); // store values as if the boxes have infinite capacity
        }

        if(maxseg[1] - minseg[1] < C[i]) { // easy case: range is small
            ans[i] = s.last_value - (minseg[1] + lazyadd[1]);
        } else { // we binary search on the segtree
            ans[i] = s.solve(C[i]);
        }
    }
    return ans;
}

Subtask #1
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 14520 KB Output is correct
2 Correct 7 ms 14540 KB Output is correct
3 Correct 9 ms 14772 KB Output is correct
4 Correct 9 ms 14796 KB Output is correct
5 Correct 9 ms 14768 KB Output is correct

Subtask #2
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 277 ms 39804 KB Output is correct
2 Correct 255 ms 38964 KB Output is correct
3 Correct 258 ms 38864 KB Output is correct

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 14524 KB Output is correct
2 Correct 126 ms 32960 KB Output is correct
3 Correct 73 ms 20520 KB Output is correct
4 Correct 280 ms 40884 KB Output is correct
5 Correct 258 ms 41252 KB Output is correct
6 Correct 279 ms 41584 KB Output is correct
7 Correct 279 ms 40936 KB Output is correct

Subtask #4
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 14508 KB Output is correct
2 Correct 7 ms 14564 KB Output is correct
3 Correct 93 ms 31404 KB Output is correct
4 Correct 60 ms 18352 KB Output is correct
5 Correct 138 ms 34508 KB Output is correct
6 Correct 135 ms 35220 KB Output is correct
7 Correct 136 ms 35736 KB Output is correct
8 Correct 129 ms 34380 KB Output is correct
9 Correct 147 ms 35916 KB Output is correct

Subtask #5
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 14520 KB Output is correct
2 Correct 7 ms 14540 KB Output is correct
3 Correct 9 ms 14772 KB Output is correct
4 Correct 9 ms 14796 KB Output is correct
5 Correct 9 ms 14768 KB Output is correct
6 Correct 277 ms 39804 KB Output is correct
7 Correct 255 ms 38964 KB Output is correct
8 Correct 258 ms 38864 KB Output is correct
9 Correct 7 ms 14524 KB Output is correct
10 Correct 126 ms 32960 KB Output is correct
11 Correct 73 ms 20520 KB Output is correct
12 Correct 280 ms 40884 KB Output is correct
13 Correct 258 ms 41252 KB Output is correct
14 Correct 279 ms 41584 KB Output is correct
15 Correct 279 ms 40936 KB Output is correct
16 Correct 7 ms 14508 KB Output is correct
17 Correct 7 ms 14564 KB Output is correct
18 Correct 93 ms 31404 KB Output is correct
19 Correct 60 ms 18352 KB Output is correct
20 Correct 138 ms 34508 KB Output is correct
21 Correct 135 ms 35220 KB Output is correct
22 Correct 136 ms 35736 KB Output is correct
23 Correct 129 ms 34380 KB Output is correct
24 Correct 147 ms 35916 KB Output is correct
25 Correct 8 ms 14544 KB Output is correct
26 Correct 58 ms 18372 KB Output is correct
27 Correct 125 ms 32596 KB Output is correct
28 Correct 264 ms 39400 KB Output is correct
29 Correct 250 ms 39856 KB Output is correct
30 Correct 257 ms 40192 KB Output is correct
31 Correct 253 ms 40256 KB Output is correct
32 Correct 257 ms 40480 KB Output is correct