Revise paste Untitled

#include <iostream>
#include <vector>
using namespace std;
const int maxn = 1e5 + 10;
const int INF = 2e9;
struct element {
    int difference, idx1, idx2, pos;
    element () {}
    element(int _difference, int _idx1, int _idx2, int _pos) {
        difference = _difference;
        idx1 = _idx1;
        idx2 = _idx2;
        pos = _pos;
    }
};
element my_merge(element A, element B) {
    if(A.difference == B.difference) {
        if(A.idx1 < B.idx1) {
            return A;
        }
        return B;
    }
    if(A.difference < B.difference) {
        return A;
    }
    return B;
}
element segment_tree[3 * maxn];
void build_tree(int L, int R, int position) {
    if(L == R) {
        segment_tree[position] = element(INF, INF, INF, INF);
    }
    else {
        int middle = (L + R) / 2;
        build_tree(L, middle, 2 * position);
        build_tree(middle + 1, R, 2 * position + 1);
        segment_tree[position] = my_merge(segment_tree[2 * position], segment_tree[2 * position + 1]);
    }
}
// L R i L R j L R
element query(int L, int R, int position, int i, int j) {
    if(i <= L and R <= j) {
        return segment_tree[position];
    }
    if(R < i or j < L) {
        return element(INF, INF, INF, INF);
    }
    int middle = (L + R) / 2;
    return my_merge(query(L, middle, 2 * position, i, j), query(middle + 1, R, 2 * position + 1, i, j));
}
void update(int L, int R, int position, int idx, element new_value) {
    if(L == R) {
        segment_tree[position] = new_value;
        return;
    }
    int middle = (L + R) / 2;
    if(idx <= middle) {
        update(L, middle, 2 * position, idx, new_value);
    }
    else {
        update(middle + 1, R, 2 * position + 1, idx, new_value);
    }
    segment_tree[position] = my_merge(segment_tree[2 * position], segment_tree[2 * position + 1]);
}
int n;
int dance[maxn], type[maxn];
int main(){
    ios_base::sync_with_stdio(false);
    cin >> n;
    for(int i = 0; i < n; i++) {
        cin >> dance[i];
    }
    for(int i = 0; i < n; i++) {
        cin >> type[i];
    }
    build_tree(0, n - 1, 1);
    for(int i = 0; i < n - 1; i++) {
        if(type[i] != type[i + 1]) {
            element e(abs(dance[i] - dance[i + 1]), i, i + 1, i);
            update(0, n - 1, 1, i, e);
        }
    }
    vector<bool> visited(n, false);
    vector<pair<int, int> > ans;
    while(true) {
        element c = query(0, n - 1, 1, 0, n - 1);
        if(c.difference == INF) {
            break;
        }
        if(visited[c.idx1] or visited[c.idx2]) {
            update(0, n - 1, 1, c.pos, element(INF, INF, INF, INF));
            continue;
        }
        ans.push_back(make_pair(c.idx1, c.idx2));
        visited[c.idx1] = true;
        visited[c.idx2] = true;
        int first_unvisited_left = c.idx1 - 1;
        int first_unvisited_right = c.idx2 + 1;
        bool L = false, R = false;
        while(first_unvisited_left >= 0) {
            if(!visited[first_unvisited_left]) {
                L = true;
                break;
            }
            first_unvisited_left--;
        }
        while(first_unvisited_right < n) {
            if(!visited[first_unvisited_right]) {
                R = true;
                break;
            }
            first_unvisited_right++;
        }
        if(L and R and first_unvisited_left >= 0 and first_unvisited_right < n and !visited[first_unvisited_left] and !visited[first_unvisited_right]) {
            if(type[first_unvisited_left] != type[first_unvisited_right]) {
                element new_value(abs(dance[first_unvisited_left] - dance[first_unvisited_right]), first_unvisited_left, first_unvisited_right, c.pos);
                update(0, n - 1, 1, c.pos, new_value);
                
            }
            else {
                update(0, n - 1, 1, c.pos, element(INF, INF, INF, INF));
            }
        }
        else {
            update(0, n - 1, 1, c.pos, element(INF, INF, INF, INF));
        }
        
    }
    cout << (int) ans.size() << endl;
    for(int i = 0; i < (int) ans.size(); i++) {
        cout << ans[i].first + 1 << " " << ans[i].second + 1 << "\n";
    }
    
    return 0;
}