Submission #135680

#	Time	Username	Problem	Language	Result	Execution time	Memory
135680		Plurm	Paths (BOI18_paths)	C++11	100 / 100	919 ms	25580 KiB

paths

#include <bits/stdc++.h>
using namespace std;
vector<int> g[300005];
long long dp[300005];
int col[300005];
vector<int> bckt[8];
int sel[8];
int n;
long long iteratePerm(int k, int c, int lv = 1){
    if(lv == c+1){
        for(int i = 1; i <= n; i++) dp[i] = 0ll;
        for(int u : bckt[sel[1]]) dp[u] = 1ll;
        for(int step = 2; step <= c; step++){
            for(int u : bckt[sel[step]]){
                for(int v : g[u]){
                    if(col[v] == sel[step-1]) dp[u] += dp[v];
                }
            }
        }
        long long sum = 0ll;
        for(int i = 1; i <= n; i++){
            if(col[i] == sel[c]){
                sum += dp[i];
            }
        }
        return sum;
    }else{
        long long sum = 0ll;
        for(int i = 1; i <= k; i++){
            bool ok = true;
            for(int j = 1; j < lv; j++){
                if(sel[j] == i) ok = false;
            }
            if(ok){
                sel[lv] = i;
                sum += iteratePerm(k, c, lv+1);
                sel[lv] = 0;
            }
        }
        return sum;
    }
}
int main(){
    int m,k;
    scanf("%d%d%d",&n,&m,&k);
    for(int i = 1; i <= n; i++){
        scanf("%d",col+i);
        bckt[col[i]].push_back(i);
    }
    for(int i = 0; i < m; i++){
        int u,v;
        scanf("%d%d",&u,&v);
        g[u].push_back(v);
        g[v].push_back(u);
    }
    long long ans = 0ll;
    for(int i = 2; i <= k; i++){
        ans += iteratePerm(k,i);
    }
    printf("%lld\n",ans);
    return 0;
}

Compilation message (stderr)

paths.cpp: In function 'int main()':
paths.cpp:45:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d",&n,&m,&k);
     ~~~~~^~~~~~~~~~~~~~~~~~~
paths.cpp:47:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",col+i);
         ~~~~~^~~~~~~~~~~~
paths.cpp:52:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&u,&v);
         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 23 / 23
• Subtask 2: 20 / 20
• Subtask 3: 27 / 27
• Subtask 4: 30 / 30