书的复制

 第四题。

原题链接：https://www.luogu.org/problem/show?pid=1281#sub

借鉴了一篇题解的思路。

#include <cstring>
#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#define maxn 1005
using namespace std;
int n,m,book[maxn];
int ans;
inline int read(){
    int num = 0;
    char c;
    bool flag = false;
    while ((c = getchar()) == ' ' || c == '
' || c == '
');
    if (c == '-')
        flag = true;
    else
        num = c - '0';
    while (isdigit(c = getchar()))
        num = num * 10 + c - '0';
    return (flag ? -1 : 1) * num;
}
bool check(int now){
    int ans=1;
    int tot=0;
    for(int i=n;i>=1;i--){
        if(tot + book[i] > now){
            tot = book[i];
            ans++;
        }
        else
            tot += book[i];
    }
    if (ans > m) 
        return false;
    else
        return true;
}
int main(){
    n = read();m = read();
    int l=0;int r =0;
    for(int i=1;i<=n;i++){
        book[i] = read();
        r += book[i];
    }
    while(l < r){
        int mid=(l+r) >> 1;
        if(check(mid)) 
            r=mid;
        else 
            l=mid+1;
    }
    ans = l;
    int out[maxn][2];
    int cnt = n;
    int now = ans;
    for(int i=m;i>=1;i--){
        out[i][2] = cnt;
        while(now - book[cnt] >= 0){
            now -= book[cnt--];
            if(cnt == 0) 
                break;
        }
        out[i][1] = cnt + 1;
        now = ans;
    }
    for(int i=1;i<=m;i++)
        printf("%d %d
",out[i][1],out[i][2]);
    return 0;
}