Java实现洛谷 P1873 砍树（StreamTokenizer+IO+二分）

P1873 砍树

输入输出样例
输入
5 20
4 42 40 26 46
输出
36

PS：

get新知识，以前只知道STringTokenizer并没有了解过StreamTokenizer，这次才知道

原来io输入的jdk提供了方法接收这个，大概感觉貌似差不多，好久没用io了，一边百度一边用

现学现卖哈哈

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StreamTokenizer;

public class 砍树 {

	public static void main(String[] args) throws IOException {
	    StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
	    PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
	    in.nextToken();
	    int n = (int)in.nval;
	    in.nextToken();
	    int m = (int)in.nval;
	    int[] s = new int[n];
	    int l = 0,r = 0;
	    for(int i = 0;i < n;i++) {
	    	in.nextToken();
	    	s[i] = (int)in.nval;
	    	r = Math.max(r, s[i]);
	    }
	    while(l <= r) {
	    	int mid = (l + r) / 2;
	    	if(judge(mid,s,m)) {
	    		l = mid + 1;
	    	}else {
	    		r = mid - 1;
	    	}
	    }
	    out.print(l - 1);
	    out.close();
	}

	public static boolean judge(int mid,int[] s,int m) {
		int sum = 0;
		for(int i = 0;i < s.length;i++) {
			if(s[i] > mid) {
				sum += (s[i] - mid);
				if(sum >= m) {
					return true;
				}
			}
		}
		return false;
	}
}