Submission #676706

#	Time	Username	Problem	Language	Result	Execution time	Memory
676706		sugartheanh	Climbers (RMI18_climbers)	C++14	100 / 100	316 ms	196060 KiB

climbers

#include<bits/stdc++.h>
using namespace std;
 
#define ll long long
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define ld long double
 
const ll maxn = 5e3 + 1, maxm = 1e6 + 1;
const ll mod = 1e9 + 7, inf = 1e9, block = 550, hb = 31, base = 1000050017, biginf = 5e18;
const ld eps = 1e-9;
 
int n;
int a[maxn];
ll dp[maxn][maxn];
set<pair<ll, pair<int, int>>> setik;
vector<int> vec;
bool is(int i, int j){
    if (a[j] <= a[j + 1]){
        return (a[j] <= a[i] && a[i] <= a[j + 1]);
    }
    else{
        return (a[j] >= a[i] && a[i] >= a[j + 1]);
    }
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0); 
    cin >> n;
    for (int i = 1; i <= n; ++i){
        cin >> a[i];
    }
    vec.pb(a[1]);
    for (int i = 2; i < n; ++i){
        if (a[i] < a[i - 1] && a[i] < a[i + 1] || a[i - 1] < a[i] && a[i] > a[i + 1]){
            vec.pb(a[i]);
        }
    }
    for (int i = 1; i <= n; ++i){
        a[i] = 0;
    }
    vec.pb(a[n]);
    n = (int)vec.size();
    for (int i = 0; i < n; ++i){
        a[i + 1] = vec[i];
    }
    for (int i = 1; i <= n; ++i){
        for (int j = 1; j <= n; ++j){
            dp[i][j] = inf * inf;
        }
    }
    dp[1][n - 1] = 0;
    setik.insert(mp(0, mp(1, n - 1)));
    while (setik.size() > 0){
        pair<ll, pair<int, int>> cur = *setik.begin(); setik.erase(cur);
        ll cost = cur.f, x = cur.s.f, y = cur.s.s;
        if (x == y || x == y + 1){
            cout << cost;
            exit(0);
        }
        if (cost > dp[x][y])
            continue;
 
        if (x > 1 && is(x - 1, y) && dp[x - 1][y] > dp[x][y] + abs(a[x] - a[x - 1])){
            dp[x - 1][y] = dp[x][y] + abs(a[x] - a[x - 1]);
            setik.insert(mp(dp[x - 1][y], mp(x - 1, y)));
        }
        if (x < n && is(x + 1, y) && dp[x + 1][y] > dp[x][y] + abs(a[x] - a[x + 1])){
            dp[x + 1][y] = dp[x][y] + abs(a[x] - a[x + 1]);
            setik.insert(mp(dp[x + 1][y], mp(x + 1, y)));
        }
        if (is(y, x) && dp[y][x] > dp[x][y] + abs(a[x] - a[y])){
            dp[y][x] = dp[x][y] + abs(a[x] - a[y]);
            setik.insert(mp(dp[y][x], mp(y, x)));
        }
        if (x > 1 && is(y, x - 1) && dp[y][x - 1] > dp[x][y] + abs(a[x] - a[y])){
            dp[y][x - 1] = dp[x][y] + abs(a[x] - a[y]);
            setik.insert(mp(dp[y][x - 1], mp(y, x - 1)));
        }
        if (is(y + 1, x) && dp[y + 1][x] > dp[x][y] + abs(a[x] - a[y + 1])){
            dp[y + 1][x] = dp[x][y] + abs(a[x] - a[y + 1]);
            setik.insert(mp(dp[y + 1][x], mp(y + 1, x)));
        }
        if (is(y + 1, x - 1) && dp[y + 1][x - 1] > dp[x][y] + abs(a[x] - a[y + 1])){
            dp[y + 1][x - 1] = dp[x][y] + abs(a[x] - a[y + 1]);
            setik.insert(mp(dp[y + 1][x - 1], mp(y + 1, x - 1)));
        }
    }
    cout << "NO\n"; 
}

Compilation message (stderr)

climbers.cpp: In function 'int main()':
climbers.cpp:38:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   38 |         if (a[i] < a[i - 1] && a[i] < a[i + 1] || a[i - 1] < a[i] && a[i] > a[i + 1]){
      |             ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 50 / 50