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Submission #217681

# Submission time Handle Problem Language Result Execution time Memory
217681 2020-03-30T12:19:46 Z mhy908 Islands (IOI08_islands) C++14
100 / 100
 1084 ms 127096 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;
vector<pii> link[1000010];
int cyc[1000010], re;
LL sum[1000010];
bool ch[1000010];

inline 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){
            ch[num]=false;
            cyc[re]=num;
            sum[re++]=temp;
            if(cyc[0]==num)return -llinf;
            return temp;
        }
    }
    ch[num]=false;
    return -llinf;
}

inline LL get_maxd(int num, int par1, int par2){
    LL ret2=0;
    ch[num]=true;
    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;
}

inline LL solve(int num){
    re=0; ret=0;
    get_cyc(num, 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:71:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
islands.cpp:74:14: 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 18 ms 23808 KB Output is correct
5 Correct 17 ms 23808 KB Output is correct
6 Correct 19 ms 23808 KB Output is correct
7 Correct 19 ms 23808 KB Output is correct
8 Correct 17 ms 23808 KB Output is correct
9 Correct 18 ms 23808 KB Output is correct
10 Correct 17 ms 23808 KB Output is correct
11 Correct 17 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 24032 KB Output is correct
2 Correct 19 ms 24064 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 24448 KB Output is correct
2 Correct 35 ms 26104 KB Output is correct
3 Correct 30 ms 24576 KB Output is correct
4 Correct 22 ms 24192 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 41 ms 26872 KB Output is correct
2 Correct 67 ms 28640 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 102 ms 32448 KB Output is correct
2 Correct 110 ms 35576 KB Output is correct
3 Correct 132 ms 41720 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 184 ms 39416 KB Output is correct
2 Correct 222 ms 54392 KB Output is correct
3 Correct 243 ms 57848 KB Output is correct
4 Correct 318 ms 69888 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 402 ms 63952 KB Output is correct
2 Correct 756 ms 90104 KB Output is correct
3 Correct 342 ms 54904 KB Output is correct
4 Correct 441 ms 78712 KB Output is correct
5 Correct 433 ms 79480 KB Output is correct
6 Correct 1084 ms 60072 KB Output is correct
7 Correct 464 ms 95352 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 500 ms 114392 KB Output is correct
2 Correct 476 ms 94456 KB Output is correct
3 Correct 491 ms 127096 KB Output is correct
4 Correct 443 ms 71032 KB Output is correct
5 Correct 429 ms 93688 KB Output is correct
6 Correct 426 ms 78072 KB Output is correct
7 Correct 998 ms 75512 KB Output is correct