解題區/解題區 - UVa

UVa 946 - A Pile of Boxes

contents

  1. 1. Problem
  2. 2. Sample Input
  3. 3. Sample Output
  4. 4. Solution

Problem

一個神祕的堆疊方式，假如燒杯大小大於要放入的燒杯，在不超過其原本的燒杯高度的情況下，則可以將其放入內部，放入內部後，可能掉入底層的燒杯中。

根據這樣的方式模擬最後堆疊的最大高度。

Sample Input

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Sample Output

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Solution

半夜爬起來寫的，總覺得檢查事件挺麻煩的事情，因此採用遞迴的方式建造，在退回的情況下查閱是否要疊在上方。

inner 表示內部底層的燒杯、outer 表示上方的燒杯，footer 表示下方的燒杯。

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#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
int inner[105], outer[105], footer[105];
int height[105], A[105];
int place(int i, int mxI, int limit) {
//	printf("down %d %d\n", A[mxI], mxI);
    if(A[mxI] < A[i]) {
        if(height[mxI] + A[i] <= limit) {
            outer[mxI] = i, footer[i] = mxI; 
            height[i] = height[mxI] + A[i];
        }
        return height[mxI] + A[i];
    }
    if(inner[mxI] == -1) {
        int h = place(i, footer[mxI], height[mxI] - A[mxI]);
        if(h <= height[mxI] - A[mxI]) // complete
            return h;
        inner[mxI] = i, footer[i] = footer[mxI];
        height[i] = height[mxI] - A[mxI] + A[i];
        return height[i];
    } else {
        mxI = inner[mxI];
        while(outer[mxI] != -1)
            mxI = outer[mxI];
        int h = place(i, mxI, height[mxI]);
        if(h == height[mxI] - A[mxI] + A[i]) {
            h = place(i, footer[mxI], height[mxI] - A[mxI]);
//			printf("check %d %d\n", h, height[mxI] - A[mxI]);
            if(h <= height[mxI] - A[mxI])
                return h;
            inner[mxI] = i, footer[i] = footer[mxI];
            height[i] = height[mxI] - A[mxI] + A[i];
            return height[i];
        } else if(h > height[mxI]) {
            if(height[mxI] + A[i] <= limit) {
                outer[mxI] = i, footer[i] = mxI;
                height[i] = height[mxI] + A[i];
            }
            return height[mxI] + A[i];
        } else {
//			puts("hello");
            return h;
        }
    }
}
int main() {
    int n;
    while(scanf("%d", &n) == 1) {
        for(int i = 0; i <= n; i++)
            inner[i] = outer[i] = footer[i] = height[i] = -1;
        A[0] = 0, height[0] = 0;
        for(int i = 1; i <= n; i++)
            scanf("%d", &A[i]);
        int mxH = 0, mxI = 0;
        for(int i = 1; i <= n; i++) {
            int h = place(i, mxI, mxH);
            if(h > mxH) {
                outer[mxI] = i, footer[i] = mxI; 
                height[i] = height[mxI] + A[i];
            }
            h = height[i];
//			printf("[%d] %d - %d mxH = %d mxI %d\n", i, A[i], h, mxH, mxI);
//			for(int j = 1; j <= i; j++)
//				printf("--------[%d] %2d * in %2d out %2d foot %2d\n", j, A[j], inner[j], outer[j], footer[j]);
            if(h > mxH)	mxH = h, mxI = i;
        }
        printf("%d\n", mxH);
    }
    return 0;
}