P2884 [USACO07MAR]Monthly Expense S

知识点：二分

这个是最小化最大值的贪心，是可行解是从大到小也就是从右到左判断的，

#include <bits/stdc++.h>

#define fi first
#define se second
#define pb push_back
#define mk make_pair
#define sz(x) ((int) (x).size())
#define all(x) (x).begin(), (x).end()

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pa;

const int N = 1e5 + 5;

int n, m, a[N];

bool check(int x) {
    int cnt = 1;
    int rec = a[0];
    if (a[0] > x) return false;
    for (int i = 1; i < n; i++) {
        if (a[i] > x) return false;
        if (rec + a[i] <= x) rec += a[i];
        else { cnt++; rec = a[i]; }
        if (cnt > m) return false;
    }
    return true;
}

void solve(int l, int r) {
    while (l < r) {
        int mid = (l + r) >> 1;
        if (check(mid)) r = mid;
        else l = mid + 1;
    }
    cout << l << endl;
}

int main() {
    cin >> n >> m;
    for (int i = 0; i < n; i++) cin >> a[i];
    solve(0, 1000000000);
    return 0;
}