Codeforces Round #811 (Div. 3)D. Color with Occurrences

题目大意：给出一个文章t和n个字符串s1,s2...sn；

　　问能否用这n个字符串将整个文章覆盖；

 

思路：贪心（最小区间覆盖)

　　记录每个字符串能够覆盖的所有位置（起点，终点，编号)

　　排序后贪心的求出是否能够将所有点覆盖

# include<iostream>
# include<bits/stdc++.h>
using namespace std;
# define int long long
# define endl "\n"
const int N = 2e5 + 10, INF = 0x3f3f3f3f3f;
struct node {
    int l, r, id;//起点，终点，编号
};
string s;
bool cmp(node a, node b) {
    if (a.l != b.l) return a.l < b.l;
    return a.r < b.r;
}
vector<node> se;
int length;

bool check(int start, string t) {
    int maxv = length - start + 1;
    if (maxv < t.size()) return false;
    for (int i = start, j = 0; i <= start + t.size() - 1; ++i, ++j) {
        if (t[j] != s[i]) return false;
    }
    return true;
}

void solve() {

    int n;
    cin >> s >> n;
    se.clear();
    length = s.size();
    s = "?" + s;
    for (int i = 1; i <= n; ++i) {
        string t;
        cin >> t;
        int len = t.size();
        for (int j = 1; j  <= length; ++j) {
            if (check(j, t)) se.push_back({j, j + len - 1, i});//记录每个字符串能够覆盖的点
        }
    }
    sort(se.begin(), se.end(), cmp);//以起始点为基准从小到大排序
    bool ok = false;
    int start = 1, ed = length;
    vector<pair<int, int>> ans;
    for (int i = 0; i < se.size(); ++i) {
        int j = i, r = -INF;

        int t = 0;
        while (j < se.size() && se[j].l <= start) {
            if (se[j].r > r)  //寻找能够覆盖区间最长的字符串
　　　　　　　　　{
                r = se[j].r;
                t = j;
            }
            j++;
        }
        if (r < start) break;
        start = r+1,i = j-1;
        ans.push_back({se[t].id,se[t].l});
        if(r>= ed){
            ok = true;
            break;
        }
    }
    if(ok){
        cout<<ans.size()<<endl;
        for(auto it:ans)cout<<it.first<<" "<<it.second<<endl;
    }
    else cout<<-1<<endl;
}
int tt;
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> tt;
    while (tt--)solve();


    return 0;
}