Rockdu's Blog

题目描述

You are given an integer n from $1$ to 10^{18} without leading zeroes.

In one move you can swap any two adjacent digits in the given number in such a way that the resulting number will not contain leading zeroes. In other words, after each move the number you have cannot contain any leading zeroes.

What is the minimum number of moves you have to make to obtain a number that is divisible by 25 ? Print -1 if it is impossible to obtain a number that is divisible by 25 .

输入输出格式

输入格式：

The first line contains an integer $n$ ( 1≤n≤1018 ). It is guaranteed that the first (left) digit of the number $n$ is not a zero.

输出格式：

If it is impossible to obtain a number that is divisible by 25 , print -1. Otherwise print the minimum number of moves required to obtain such number.

Note that you can swap only adjacent digits in the given number.

输入输出样例

5071

4

705

1

1241367

-1

说明

In the first example one of the possible sequences of moves is 5071 $\to$ 5701 $\to$ 7501 $\to$ 7510 $\to$ 7150.

本来水着div3多愉快，突然遇到这个细节题，本来觉得就是把末尾移成00\25\50\75，应该多水的结果被坑惨了。交了5遍才把细节都处理完，就挂上来。

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
char s[20];
int pos5, pos2, pos0, pos0_2, pos7, len, ans = 0x7fffffff;
int zeros, z1, z2;

int Gans(int x, int y, int z) {
	int lenx = len - 1 - x, leny = len - 1 - y;
	if(y == len - 1) leny = 0;
	if(x < y) lenx = len - 2 - x;
	if(x == 0 || y == 0) return lenx + leny + z;
	return lenx + leny;
}

int main() {
	pos5 = pos2 = pos0 = pos0_2 = pos7 = -1;
	scanf("%s", s);
	len = strlen(s);
	for(register int i = 1; i < len && s[i] == '0'; ++i) ++zeros;
	for(register int i = 0; i < len; ++i) {
		if(s[i] == '5') pos5 = i;
		if(s[i] == '7') pos7 = i;
		if(s[i] == '2') pos2 = i;
		if(s[i] == '0')
			if(pos0) pos0 = pos0_2, pos0_2 = i;
			else pos0 = i;
	}
	swap(pos0, pos0_2), z1 = zeros, z2 = zeros;
	if(~pos0_2 && pos0_2 <= zeros) --z1;
	if(~pos0 && pos0 <= zeros) --z2, --z1;
	if(~pos7 && ~pos5) ans = min(ans, Gans(pos7, pos5, zeros));
	if(~pos2 && ~pos5) ans = min(ans, Gans(pos2, pos5, zeros));
	if(~pos5 && ~pos0) ans = min(ans, Gans(pos5, pos0, z1));
	if(~pos0_2 && ~pos0) ans = min(ans, Gans(pos0_2, pos0, z2));
	printf("%d\n", ans == 0x7fffffff ? -1 : ans);
	return 0;
}