Problem p00463 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// #include <utility>
// #include <memory>
// #include <functional>
// #include <deque>
// #include <cctype>
// #include <ctime>
// #include <numeric>
// #include <list>
// #include <iomanip>

// #if __cplusplus >= 201103L
// #include <array>
// #include <tuple>
// #include <initializer_list>
// #include <forward_list>
//
// #define cauto const auto&
// #else

// #endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long>> vvll, vvLL;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) reep((i), 0, (n))
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(), (v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif
#define LDcout(x, n) fixed << setprecision(n) << x

#define MOD 1000000007LL
#define EPS 1e-8
static const int INF = 1 << 24;

void mainmain() {
  int n, m, h, K;
  while (cin >> n >> m >> h >> K, n) {
    vint v(n);
    set<pii> se;
    rep(i, n) cin >> v[i];
    vector<pii> w(m);
    rep(i, m) cin >> w[i].S >> w[i].F, w[i].S--;
    sort(ALL(w));
    vint pos(n);
    rep(i, n) pos[i] = i;
    rep(i, m) {
      se.insert(minmax(pos[w[i].S], pos[w[i].S + 1]));
      swap(pos[w[i].S], pos[w[i].S + 1]);
    }
    int ans = 0;
    vint score(n);
    rep(i, n) {
      if (pos[i] < K) {
        ans += v[i];
      }
      score[pos[i]] = v[i];
    }
    int tmp = 0;
    for (pii x : se) {
      if (x.F < K && x.S >= K) {
        tmp = max(tmp, score[x.F] - score[x.S]);
      }
    }
    cout << ans - tmp << endl;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(0);
  mainmain();
}

Error: WA

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// #include <utility>
// #include <memory>
// #include <functional>
// #include <deque>
// #include <cctype>
// #include <ctime>
// #include <numeric>
// #include <list>
// #include <iomanip>

// #if __cplusplus >= 201103L
// #include <array>
// #include <tuple>
// #include <initializer_list>
// #include <forward_list>
//
// #define cauto const auto&
// #else

// #endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long>> vvll, vvLL;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) reep((i), 0, (n))
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(), (v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif
#define LDcout(x, n) fixed << setprecision(n) << x

#define MOD 1000000007LL
#define EPS 1e-8
static const int INF = 1 << 24;

void mainmain() {
  int n, m, h, K;
  while (cin >> n >> m >> h >> K, n) {
    vint v(n);
    set<pii> se;
    rep(i, n) cin >> v[i];
    vector<pii> w(m);
    rep(i, m) cin >> w[i].S >> w[i].F;
    sort(ALL(w));
    vint pos(n);
    rep(i, n) pos[i] = i;
    rep(i, m) {
      se.insert(minmax(pos[w[i].S], pos[w[i].S + 1]));
      swap(pos[w[i].S], pos[w[i].S + 1]);
    }
    int ans = 0;
    vint score(n);
    rep(i, n) {
      if (pos[i] < K) {
        ans += v[i];
      }
      score[pos[i]] = v[i];
    }
    int tmp = 0;
    for (pii x : se) {
      if (x.F < K && x.S >= K) {
        tmp = max(tmp, score[x.F] - score[x.S]);
      }
    }
    cout << ans - tmp << endl;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(0);
  mainmain();
}