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Submission #217679

# Submission time Handle Problem Language Result Execution time Memory
217679 2020-03-30T12:13:02 Z mhy908 Islands (IOI08_islands) C++14
80 / 100
 1315 ms 131076 KB 
#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define F first
#define S second
using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
const LL llinf=1987654321987654321;

int n;
LL ret, ans;
list<pii> link[1000010];
int cyc[1000010], re;
LL sum[1000010];
bool ch[1000010];

void chdfs(int num, int par1, int par2){
    ch[num]=true;
    for(auto i:link[num]){
        if(i.F==par1||i.F==par2)continue;
        chdfs(i.F, num, par2);
    }
}

LL get_cyc(int num, int par){
    if(ch[num]){
        cyc[re]=num;
        sum[re++]=0;
        return 0;
    }
    ch[num]=true;
    int t=0;
    for(auto i:link[num]){
        if(i.F==par&&!t){
            t++;
            continue;
        }
        LL temp=get_cyc(i.F, num)+i.S;
        if(temp>=0){
            cyc[re]=num;
            sum[re++]=temp;
            if(cyc[0]==num)return -llinf;
            return temp;
        }
    }
    return -llinf;
}

LL get_maxd(int num, int par1, int par2){
    LL ret2=0;
    for(auto i:link[num]){
        if(i.F==par1||i.F==par2)continue;
        LL temp=get_maxd(i.F, num, num)+i.S;
        ret=max(ret, ret2+temp);
        ret2=max(ret2, temp);
    }
    return ret2;
}

LL solve(int num){
    re=0; ret=0;
    get_cyc(num, 0);
    chdfs(cyc[0], 0, cyc[0]);
    LL max1=llinf, max2=-llinf, dia=sum[--re];
    for(int i=0; i<re; i++){
        LL tmp=get_maxd(cyc[i], cyc[(i+re-1)%re], cyc[(i+1)%re]);
        ret=max(ret, sum[i]+tmp-max1);
        ret=max(ret, dia-sum[i]+tmp+max2);
        max2=max(max2, sum[i]+tmp);
        max1=min(max1, sum[i]-tmp);
    }
    return ret;
}

int main(){
    scanf("%d", &n);
    for(int i=1; i<=n; i++){
        int a, b;
        scanf("%d %d", &a, &b);
        link[i].pb(mp(a, b));
        link[a].pb(mp(i, b));
    }
    for(int i=1; i<=n; i++){
        if(ch[i])continue;
        ans+=solve(i);
    }
    printf("%lld", ans);
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:77:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
islands.cpp:80:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 23808 KB Output is correct
2 Correct 17 ms 23808 KB Output is correct
3 Correct 18 ms 23808 KB Output is correct
4 Correct 17 ms 23808 KB Output is correct
5 Correct 17 ms 23808 KB Output is correct
6 Correct 17 ms 23808 KB Output is correct
7 Correct 17 ms 23808 KB Output is correct
8 Correct 17 ms 23808 KB Output is correct
9 Correct 17 ms 23808 KB Output is correct
10 Correct 18 ms 23808 KB Output is correct
11 Correct 18 ms 23808 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 23936 KB Output is correct
2 Correct 18 ms 23936 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23936 KB Output is correct
2 Correct 20 ms 24192 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 24960 KB Output is correct
2 Correct 39 ms 27128 KB Output is correct
3 Correct 31 ms 25216 KB Output is correct
4 Correct 25 ms 24448 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 46 ms 28408 KB Output is correct
2 Correct 61 ms 31480 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 122 ms 38008 KB Output is correct
2 Correct 125 ms 44024 KB Output is correct
3 Correct 155 ms 50808 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 191 ms 50428 KB Output is correct
2 Correct 261 ms 70520 KB Output is correct
3 Correct 291 ms 81272 KB Output is correct
4 Correct 337 ms 93160 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 455 ms 87544 KB Output is correct
2 Correct 891 ms 124664 KB Output is correct
3 Correct 375 ms 75768 KB Output is correct
4 Correct 507 ms 109944 KB Output is correct
5 Correct 484 ms 109816 KB Output is correct
6 Correct 1315 ms 85240 KB Output is correct
7 Runtime error 438 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 450 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -