CodeForces822C【贪心】

思路：
对于每个位置，维护其左边以区间长度为 len 的最小值。

#include<bits/stdc++.h>using namespace std;typedef long long LL;const int N = 2e5 + 10;struct asd{    int Left, Right;    LL cos;}q[N];int n, x;vector<asd>a[N], b[N];LL num[N];int main(){    scanf("%d%d",&n,&x);    for(int i=1;i<=n;i++){        scanf("%d%d%I64d",&q[i].Left, &q[i].Right, &q[i].cos);        a[q[i].Left].push_back(q[i]);        b[q[i].Right].push_back(q[i]);    }    for(int i=1;i<=200000;i++) num[i] = 1e18;    LL ans = 1e18;    for(int i=1;i<=200000;i++){        int sz = a[i].size();        int len;        for(int j=0;j<sz;j++){            len = a[i][j].Right - a[i][j].Left + 1;            if(x > len){                len = x - len;                if(num[len] != 1e18) ans = min(ans, num[len] + a[i][j].cos);            }        }        sz = b[i].size();        for(int j=0;j<sz;j++){            len = b[i][j].Right - b[i][j].Left + 1;            num[len] = min(num[len], b[i][j].cos);        }    }    if(ans == 1e18) puts("-1");    else printf("%I64d\n", ans);    return 0;}