Codeforces 551C GukiZ hates Boxes 二分答案

#include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <cstdio>
#include <map>
#include <queue>
#include <algorithm>
#include <stack>
#include <cstring>
#include <cmath>
#include <set>
#include <vector>
using namespace std;
template <class T>
inline bool rd(T &ret) {
	char c; int sgn;
	if (c = getchar(), c == EOF) return 0;
	while (c != '-' && (c<'0' || c>'9')) c = getchar();
	sgn = (c == '-') ? -1 : 1;
	ret = (c == '-') ? 0 : (c - '0');
	while (c = getchar(), c >= '0'&&c <= '9') ret = ret * 10 + (c - '0');
	ret *= sgn;
	return 1;
}
template <class T>
inline void pt(T x) {
	if (x < 0) {
		putchar('-');
		x = -x;
	}
	if (x > 9) pt(x / 10);
	putchar(x % 10 + '0');
}
typedef long long ll;
typedef pair<ll, ll> pii;
const int inf = 1e9;
const int N = 1e5 + 10;
int n, m;
int a[N], b[N];
bool ok(ll x) {
	for (int i = 1; i <= n; i++)b[i] = a[i];
	int top = n, tmp = m;
	while (tmp-->0 && top) {
		ll lef = x - top;
		while (lef && top) {
			if (b[top] == 0) { top--;continue; }
			if (b[top] <= lef) {
				lef -= b[top--];
			}
			else { b[top] -= (int)lef;lef = 0; }
		}
	}
	while (top && b[top] == 0)top--;//找到最后一个并且不是0的点
	return top == 0;
}
int main() {
	rd(n); rd(m);
	int d = 1;
	for (int i = 1; i <= n; i++) {
		rd(a[i]);
	}
	while (a[n] == 0)n--; //把最后的0删掉
	ll l = 1, r = 1e15, ans;
	while (l <= r) {
		ll mid = (l + r) >> 1;
		if (ok(mid)) {
			ans = mid;
			r = mid - 1;
		}
		else l = mid + 1;
	}
	pt(ans);
	return 0;
}

版权声明：本文为博主原创文章，未经博主允许不得转载。