oj.uz

Submission #504134

# Submission time Handle Problem Language Result Execution time Memory
504134 2022-01-09T22:12:18 Z gavgav Fountain (eJOI20_fountain) C++17
100 / 100
 105 ms 10464 KB 
// This is Lucallie's solving but with some optimizations and explanations, 'cause when I solved this problem with own code I wondered why this solving is so fast and try to understand it, but he's code is weird and strange, but super fast.
#include <bits/stdc++.h>
using namespace std;
struct reservoir{
    int diameter;
    short capacity; // 1 <= diameter <= 10^9 | 1 <= capacity <= 1000
};
struct query{
    int level, volume, answer; // 1 <= volume <= 10^9
};
int main() {
    int height, queries_number, necessary, top, i, j; // 2 <= height <= 10^5 | 1 <= queries 2 * 10^5
    scanf( "%d%d", &height, &queries_number);
    int previous_request[queries_number + 1], // i-th number of previous_request keeps index of previous request that opened tap of this request
        last_request[height + 1] {}, // i-th number of last_request keeps index of last query that open tap at i-th reservoir
        necessary_water[height + 1], // i-th number of necessary_water keeps volume of water which need to reach waterways from i-th + 1 reservoir
        stream[height + 1];
    reservoir reservoirs[height + 1];
    query queries[queries_number + 1];
    reservoirs[0].diameter = 1000000001; // maximum possible diameter + 1
    reservoirs[0].capacity = 0;
    for (i = 1; i <= height; ++i)
        scanf( "%d%hd", &reservoirs[i].diameter, &reservoirs[i].capacity);
    for (i = 1; i <= queries_number; ++i) {
        scanf( "%d%d", &queries[i].level, &queries[i].volume);
        previous_request[i] = last_request[queries[i].level];
        last_request[queries[i].level] = i;
    }
    stream[0] = 0;
    top = 0;
    necessary = 0;
    int left, middle, right;
    for (i = height; i > 0; --i) {
        while (reservoirs[i].diameter >= reservoirs[stream[top]].diameter) {
            necessary -= reservoirs[stream[top]].capacity;
            --top;
        }
        ++top;
        stream[top] = i;
        necessary_water[top] = necessary;
        necessary += reservoirs[i].capacity;
        j = last_request[i];
        while (j != 0) {
            right = top + 1;
            left = 0;
            while (right - left > 1 ) {
                middle = (right + left) / 2;
                if (necessary - necessary_water[middle] >= queries[j].volume)
                    left = middle;
                else
                    right = middle;
            }
            queries[j].answer = stream[left];
            j = previous_request[j];
        }
    }
    for (i = 1; i <= queries_number; ++i){
        printf("%d\n", queries[i].answer);
    }
}

Compilation message

fountain.cpp: In function 'int main()':
fountain.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     scanf( "%d%d", &height, &queries_number);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fountain.cpp:23:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |         scanf( "%d%hd", &reservoirs[i].diameter, &reservoirs[i].capacity);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fountain.cpp:25:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |         scanf( "%d%d", &queries[i].level, &queries[i].volume);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 288 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 296 KB Output is correct
5 Correct 1 ms 332 KB Output is correct
6 Correct 1 ms 372 KB Output is correct
7 Correct 1 ms 332 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 65 ms 7632 KB Output is correct
2 Correct 70 ms 8064 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 288 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 296 KB Output is correct
5 Correct 1 ms 332 KB Output is correct
6 Correct 1 ms 372 KB Output is correct
7 Correct 1 ms 332 KB Output is correct
8 Correct 65 ms 7632 KB Output is correct
9 Correct 70 ms 8064 KB Output is correct
10 Correct 1 ms 304 KB Output is correct
11 Correct 41 ms 4948 KB Output is correct
12 Correct 105 ms 10464 KB Output is correct
13 Correct 89 ms 10052 KB Output is correct
14 Correct 73 ms 9372 KB Output is correct
15 Correct 65 ms 9796 KB Output is correct