Submission #88891

#	Time	Username	Problem	Language	Result	Execution time	Memory
88891		sailormoon	Triumphal arch (POI13_luk)	C++14	90 / 100	1145 ms	38124 KiB

luk

    #include <string>
    #include <algorithm>
    #include <iostream>
    #include <vector>
     
    using namespace std;
    int canHandle(int v, int crs);
    vector<vector<int>> graph (1000001); // size
    bool visited[1000001];
     
     
    int main() { 
        int n, a, b, start = 0, midpoint, end, cities; // n -> towns, a -> from, b -> to
        scanf("%d", &n);
        cities = n; // for further usage
        end = n; // last point
        n--;
        while (n--) {
            scanf("%d %d", &a, &b);
            graph[a].push_back(b);
            graph[b].push_back(a);
        }
     
        // binary search for sufficient amount of crews
        while (start < end) {
            midpoint = (start + end) / 2;
            for (int i = 0; i < cities; i++) visited[i] = false; // clear array 
            if (canHandle(1, midpoint) == 0) 
                end = midpoint;
            else   
                start = midpoint + 1; 
        }
        // if (start == 1) start = 0;
        printf("%d\n", start);
     
        return 0;
    }
     
    int canHandle(int v, int crs) {
        int num_children = 0, need_crews = 0;
        visited[v] = true;
        for (int i = 0; i < graph[v].size(); i++) {
            if (!visited[graph[v][i]]) { 
                num_children++;
                need_crews += canHandle(graph[v][i], crs);
            }
        }
        if (num_children + need_crews - crs <= 0)
            return 0;
        return num_children + need_crews - crs;
    }

Compilation message (stderr)

luk.cpp: In function 'int canHandle(int, int)':
luk.cpp:42:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < graph[v].size(); i++) {
                         ~~^~~~~~~~~~~~~~~~~
luk.cpp: In function 'int main()':
luk.cpp:14:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &n);
         ~~~~~^~~~~~~~~~
luk.cpp:19:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %d", &a, &b);
             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10