45 lines
1.6 KiB
C++
45 lines
1.6 KiB
C++
#include <bits/stdc++.h>
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// https://www.bilibili.com/video/BV1iC4y1p77u
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// 要想理解明白，需要画图，按视频的图来理解就简单明白了
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//动态二维数据应用：行列转换
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using namespace std;
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int y[101]; //y[i]:第i个数据所在的列
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int c[101]; //c[j]:第j列的数据个数
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int main() {
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int i, j, M = 5, K = 8;
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int w[8][3] = {{1, 2, 12},
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{1, 4, 14},
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{2, 2, 22},
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{2, 5, 25},
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{3, 4, 34},
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{4, 1, 41},
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{4, 3, 43},
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{4, 5, 45}};
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//读入数据到我们定义的数据结构中，其实就是两个数组模拟一个M*N的大数组，有数据的留用，无数据的不占用资源
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for (i = 1; i <= K; i++) {
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y[i] = w[i - 1][1];//列
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c[y[i]]++;//每列数据个数
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}
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//给指针a申请M+1个int型指针空间
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int **a = new int *[M + 1];//指针数组 a指向指针数组的开头
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//给第i列指针a[i]申请c[i]个int型空间
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for (i = 1; i <= M; i++)a[i] = new int[c[i]];//放弃a[0],从a[1]开始创建动态数组，数组的大小就是c[i]
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//收集k个数据到相应的y[i]列中
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for (i = 1; i <= K; i++) {
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*a[y[i]] = w[i - 1][2]; //向指针指向的数组元素进行赋值
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printf("*a[%d]=%d\n", y[i], *a[y[i]]);
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a[y[i]]++;//数组指针下移,
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}
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//列优先输出数据
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for (i = 1; i <= M; i++) {
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a[i] -= c[i];//数组指针回到每列前面
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for (j = 1; j <= c[i]; j++, a[i]++)
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printf("%d ", *a[i]);//输出数据
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}
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return 0;
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}
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